Merge pull request #108 from ucan-wg/cont-test

container: add a helper for test only

.github/workflows/bench.yml

@@ -2,7 +2,7 @@ name: go continuous benchmark
 on:
   push:
     branches:
-      - v1
+      - main
 
 permissions:
   contents: write
@@ -14,7 +14,7 @@ jobs:
     runs-on: ubuntu-latest
     steps:
       - uses: actions/checkout@v4
-      - uses: actions/setup-go@v4
+      - uses: actions/setup-go@v5
         with:
           go-version: "stable"
       - name: Run benchmark

.github/workflows/gotest.yml

@@ -13,8 +13,8 @@ jobs:
     runs-on: ${{ matrix.os }}-latest
     name: ${{ matrix.os}} (go ${{ matrix.go }})
     steps:
-      - uses: actions/checkout@v2
-      - uses: actions/setup-go@v2
+      - uses: actions/checkout@v4
+      - uses: actions/setup-go@v5
         with:
           go-version: ${{ matrix.go }}
       - name: Go information

Readme.md

@@ -0,0 +1,77 @@
+<div align="center">
+  <a href="https://github.com/ucan-wg/go-ucan" target="_blank">
+    <img src="https://raw.githubusercontent.com/ucan-wg/go-ucan/v1/assets/logo.png" alt="go-ucan Logo" height="250"></img>
+  </a>
+
+  <h1 align="center">go-ucan</h1>
+
+  <p>
+    <img src="https://img.shields.io/badge/UCAN-v1.0.0--rc.1-blue" alt="UCAN v1.0.0-rc.1">
+    <a href="https://github.com/ucan-wg/go-ucan/tags">
+        <img alt="GitHub Tag" src="https://img.shields.io/github/v/tag/ucan-wg/go-ucan">
+    </a>
+    <a href="https://github.com/ucan-wg/go-ucan/actions?query=">
+      <img src="https://github.com/ucan-wg/go-ucan/actions/workflows/gotest.yml/badge.svg" alt="Build Status">
+    </a>
+    <a href="https://ucan-wg.github.io/go-ucan/dev/bench/">
+        <img alt="Go benchmarks" src="https://img.shields.io/badge/Benchmarks-go-blue">
+    </a>
+    <a href="https://github.com/ucan-wg/go-ucan/blob/v1/LICENSE.md">
+        <img alt="Apache 2.0 + MIT License" src="https://img.shields.io/badge/License-Apache--2.0+MIT-green">
+    </a>
+    <a href="https://pkg.go.dev/github.com/ucan-wg/go-ucan">
+      <img src="https://img.shields.io/badge/Docs-godoc-blue" alt="Docs">
+    </a>
+    <a href="https://discord.gg/JSyFG6XgVM">
+      <img src="https://img.shields.io/static/v1?label=Discord&message=join%20us!&color=mediumslateblue" alt="Discord">
+    </a>
+  </p>
+</div>
+
+This is a go library to help the next generation of web and decentralized applications make use
+of UCANs in their authorization flows.
+
+User Controlled Authorization Networks (UCANs) are a way of doing authorization where users are fully in control. OAuth is designed for a centralized world, UCAN is the distributed user controlled version.
+
+## Resources
+
+### Specifications
+
+The UCAN specification is separated in multiple sub-spec:
+- [Main specification](https://github.com/ucan-wg/spec)
+- [Delegation](https://github.com/ucan-wg/delegation/tree/v1_ipld)
+- [Invocation](https://github.com/ucan-wg/invocation)
+
+Not implemented yet:
+- [Revocation](https://github.com/ucan-wg/revocation/tree/first-draft)
+- [Promise](https://github.com/ucan-wg/promise/tree/v1-rc1)
+
+### Talks
+
+- [Decentralizing Auth, and UCAN Too - Brooklyn Zelenka (2023)](https://www.youtube.com/watch?v=MuHfrqw9gQA)
+- [What's New in UCAN 1.0 - Brooklyn Zelenka (2024)](https://www.youtube.com/watch?v=-uohQzZcwF4)
+
+## Status
+
+`go-ucan` currently support the required parts of the UCAN specification: the main specification, delegation and invocation.
+
+Besides that, `go-ucan` also includes:
+- a simplified [DID](https://www.w3.org/TR/did-core/) and [did-key](https://w3c-ccg.github.io/did-method-key/) implementation
+- a [token container](https://github.com/ucan-wg/go-ucan/tree/v1/pkg/container) with CBOR and CAR format, to package and carry tokens together, see [SPEC](pkg/container/SPEC.md)
+- support for encrypted values in token's metadata
+
+## Getting Help
+
+For usage questions, usecases, or issues reach out to us in our `go-ucan`
+[Discord channel](https://discord.gg/3EHEQ6M8BC).
+
+We would be happy to try to answer your question or try opening a new issue on
+Github.
+
+## UCAN Gopher
+
+Artwork by [Bruno Monts](https://www.instagram.com/bruno_monts). Thank you [Renee French](http://reneefrench.blogspot.com/) for creating the [Go Gopher](https://blog.golang.org/gopher)
+
+## License
+
+This project is licensed under the double license [Apache 2.0 + MIT](https://github.com/ucan-wg/go-ucan/blob/v1/LICENSE.md).

did/did.go

@@ -78,7 +78,7 @@ func MustParse(str string) DID {
 
 // Defined tells if the DID is defined, not equal to Undef.
 func (d DID) Defined() bool {
-	return d.code == 0 || len(d.bytes) > 0
+	return d.code != 0 || len(d.bytes) > 0
 }
 
 // PubKey returns the public key encapsulated by the did:key.
@@ -102,6 +102,9 @@ func (d DID) PubKey() (crypto.PubKey, error) {
 
 // String formats the decentralized identity document (DID) as a string.
 func (d DID) String() string {
+	if d == Undef {
+		return "(undefined)"
+	}
 	key, _ := mbase.Encode(mbase.Base58BTC, []byte(d.bytes))
 	return "did:key:" + key
 }

did/didtest/crypto.go

@@ -0,0 +1,150 @@
+// Package didtest provides Personas that can be used for testing.  Each
+// Persona has a name, crypto.PrivKey and associated crypto.PubKey and
+// did.DID.
+package didtest
+
+import (
+	"fmt"
+
+	"github.com/libp2p/go-libp2p/core/crypto"
+
+	"github.com/ucan-wg/go-ucan/did"
+)
+
+const (
+	alicePrivKeyB64 = "CAESQHdNJLBBiuc1AdwPHBkubB2KS1p0cv2JEF7m8tfwtrcm5ajaYPm+XmVCmtcHOF2lGDlmaiDA7emfwD3IrcyES0M="
+	bobPrivKeyB64   = "CAESQHBz+AIop1g+9iBDj+ufUc/zm9/ry7c6kDFO8Wl/D0+H63V9hC6s9l4npf3pYEFCjBtlR0AMNWMoFQKSlYNKo20="
+	carolPrivKeyB64 = "CAESQPrCgkcHnYFXDT9AlAydhPECBEivEuuVx9dJxLjVvDTmJIVNivfzg6H4mAiPfYS+5ryVVUZTHZBzvMuvvvG/Ks0="
+	danPrivKeyB64   = "CAESQCgNhzofKhC+7hW6x+fNd7iMPtQHeEmKRhhlduf/I7/TeOEFYAEflbJ0sAhMeDJ/HQXaAvsWgHEbJ3ZLhP8q2B0="
+	erinPrivKeyB64  = "CAESQKhCJo5UBpQcthko8DKMFsbdZ+qqQ5oc01CtLCqrE90dF2GfRlrMmot3WPHiHGCmEYi5ZMEHuiSI095e/6O4Bpw="
+	frankPrivKeyB64 = "CAESQDlXPKsy3jHh7OWTWQqyZF95Ueac5DKo7xD0NOBE5F2BNr1ZVxRmJ2dBELbOt8KP9sOACcO9qlCB7uMA1UQc7sk="
+)
+
+// Persona is a generic participant used for cryptographic testing.
+type Persona int
+
+// The provided Personas were selected from the first few generic
+// participants listed in this [table].
+//
+// [table]: https://en.wikipedia.org/wiki/Alice_and_Bob#Cryptographic_systems
+const (
+	PersonaAlice Persona = iota + 1
+	PersonaBob
+	PersonaCarol
+	PersonaDan
+	PersonaErin
+	PersonaFrank
+)
+
+var privKeys map[Persona]crypto.PrivKey
+
+func init() {
+	privKeys = make(map[Persona]crypto.PrivKey, 6)
+	for persona, privKeyCfg := range privKeyB64() {
+		privKeyMar, err := crypto.ConfigDecodeKey(privKeyCfg)
+		if err != nil {
+			return
+		}
+
+		privKey, err := crypto.UnmarshalPrivateKey(privKeyMar)
+		if err != nil {
+			return
+		}
+
+		privKeys[persona] = privKey
+	}
+}
+
+// DID returns a did.DID based on the Persona's Ed25519 public key.
+func (p Persona) DID() did.DID {
+	d, err := did.FromPrivKey(p.PrivKey())
+	if err != nil {
+		panic(err)
+	}
+	return d
+}
+
+// Name returns the username of the Persona.
+func (p Persona) Name() string {
+	name, ok := map[Persona]string{
+		PersonaAlice: "Alice",
+		PersonaBob:   "Bob",
+		PersonaCarol: "Carol",
+		PersonaDan:   "Dan",
+		PersonaErin:  "Erin",
+		PersonaFrank: "Frank",
+	}[p]
+	if !ok {
+		panic(fmt.Sprintf("Unknown persona: %v", p))
+	}
+
+	return name
+}
+
+// PrivKey returns the Ed25519 private key for the Persona.
+func (p Persona) PrivKey() crypto.PrivKey {
+	res, ok := privKeys[p]
+	if !ok {
+		panic(fmt.Sprintf("Unknown persona: %v", p))
+	}
+	return res
+}
+
+func (p Persona) PrivKeyConfig() string {
+	res, ok := privKeyB64()[p]
+	if !ok {
+		panic(fmt.Sprintf("Unknown persona: %v", p))
+	}
+	return res
+}
+
+// PubKey returns the Ed25519 public key for the Persona.
+func (p Persona) PubKey() crypto.PubKey {
+	return p.PrivKey().GetPublic()
+}
+
+// PubKeyConfig returns the marshaled and encoded Ed25519 public key
+// for the Persona.
+func (p Persona) PubKeyConfig() string {
+	pubKeyMar, err := crypto.MarshalPublicKey(p.PrivKey().GetPublic())
+	if err != nil {
+		panic(err)
+	}
+	return crypto.ConfigEncodeKey(pubKeyMar)
+}
+
+func privKeyB64() map[Persona]string {
+	return map[Persona]string{
+		PersonaAlice: alicePrivKeyB64,
+		PersonaBob:   bobPrivKeyB64,
+		PersonaCarol: carolPrivKeyB64,
+		PersonaDan:   danPrivKeyB64,
+		PersonaErin:  erinPrivKeyB64,
+		PersonaFrank: frankPrivKeyB64,
+	}
+}
+
+// Personas returns an (alphabetically) ordered list of the defined
+// Persona values.
+func Personas() []Persona {
+	return []Persona{
+		PersonaAlice,
+		PersonaBob,
+		PersonaCarol,
+		PersonaDan,
+		PersonaErin,
+		PersonaFrank,
+	}
+}
+
+// DidToName retrieve the persona's name from its DID.
+func DidToName(d did.DID) string {
+	return map[did.DID]string{
+		PersonaAlice.DID(): "Alice",
+		PersonaBob.DID():   "Bob",
+		PersonaCarol.DID(): "Carol",
+		PersonaDan.DID():   "Dan",
+		PersonaErin.DID():  "Erin",
+		PersonaFrank.DID(): "Frank",
+	}[d]
+}

go.mod

@@ -4,16 +4,17 @@ go 1.23
 
 require (
 	github.com/decred/dcrd/dcrec/secp256k1/v4 v4.3.0
-	github.com/ipfs/go-cid v0.4.1
+	github.com/ipfs/go-cid v0.5.0
 	github.com/ipld/go-ipld-prime v0.21.0
-	github.com/lestrrat-go/jwx/v2 v2.1.1
-	github.com/libp2p/go-libp2p v0.36.3
+	github.com/lestrrat-go/jwx/v2 v2.1.3
+	github.com/libp2p/go-libp2p v0.33.0
 	github.com/mr-tron/base58 v1.2.0
 	github.com/multiformats/go-multibase v0.2.0
 	github.com/multiformats/go-multicodec v0.9.0
 	github.com/multiformats/go-multihash v0.2.3
 	github.com/multiformats/go-varint v0.0.7
-	github.com/stretchr/testify v1.9.0
+	github.com/stretchr/testify v1.10.0
+	golang.org/x/crypto v0.32.0
 	gotest.tools/v3 v3.5.1
 )
 
@@ -21,7 +22,7 @@ require (
 	github.com/davecgh/go-spew v1.1.1 // indirect
 	github.com/goccy/go-json v0.10.3 // indirect
 	github.com/google/go-cmp v0.5.9 // indirect
-	github.com/klauspost/cpuid/v2 v2.2.8 // indirect
+	github.com/klauspost/cpuid/v2 v2.2.9 // indirect
 	github.com/lestrrat-go/blackmagic v1.0.2 // indirect
 	github.com/lestrrat-go/httpcc v1.0.1 // indirect
 	github.com/lestrrat-go/httprc v1.0.6 // indirect
@@ -34,9 +35,8 @@ require (
 	github.com/polydawn/refmt v0.89.0 // indirect
 	github.com/segmentio/asm v1.2.0 // indirect
 	github.com/spaolacci/murmur3 v1.1.0 // indirect
-	golang.org/x/crypto v0.25.0 // indirect
-	golang.org/x/sys v0.22.0 // indirect
-	google.golang.org/protobuf v1.34.2 // indirect
+	golang.org/x/sys v0.29.0 // indirect
+	google.golang.org/protobuf v1.36.0 // indirect
 	gopkg.in/check.v1 v1.0.0-20190902080502-41f04d3bba15 // indirect
 	gopkg.in/yaml.v3 v3.0.1 // indirect
 	lukechampine.com/blake3 v1.3.0 // indirect

go.sum

@@ -16,14 +16,14 @@ github.com/google/go-cmp v0.5.9 h1:O2Tfq5qg4qc4AmwVlvv0oLiVAGB7enBSJ2x2DqQFi38=
 github.com/google/go-cmp v0.5.9/go.mod h1:17dUlkBOakJ0+DkrSSNjCkIjxS6bF9zb3elmeNGIjoY=
 github.com/gopherjs/gopherjs v0.0.0-20181017120253-0766667cb4d1 h1:EGx4pi6eqNxGaHF6qqu48+N2wcFQ5qg5FXgOdqsJ5d8=
 github.com/gopherjs/gopherjs v0.0.0-20181017120253-0766667cb4d1/go.mod h1:wJfORRmW1u3UXTncJ5qlYoELFm8eSnnEO6hX4iZ3EWY=
-github.com/ipfs/go-cid v0.4.1 h1:A/T3qGvxi4kpKWWcPC/PgbvDA2bjVLO7n4UeVwnbs/s=
-github.com/ipfs/go-cid v0.4.1/go.mod h1:uQHwDeX4c6CtyrFwdqyhpNcxVewur1M7l7fNU7LKwZk=
+github.com/ipfs/go-cid v0.5.0 h1:goEKKhaGm0ul11IHA7I6p1GmKz8kEYniqFopaB5Otwg=
+github.com/ipfs/go-cid v0.5.0/go.mod h1:0L7vmeNXpQpUS9vt+yEARkJ8rOg43DF3iPgn4GIN0mk=
 github.com/ipld/go-ipld-prime v0.21.0 h1:n4JmcpOlPDIxBcY037SVfpd1G+Sj1nKZah0m6QH9C2E=
 github.com/ipld/go-ipld-prime v0.21.0/go.mod h1:3RLqy//ERg/y5oShXXdx5YIp50cFGOanyMctpPjsvxQ=
 github.com/jtolds/gls v4.20.0+incompatible h1:xdiiI2gbIgH/gLH7ADydsJ1uDOEzR8yvV7C0MuV77Wo=
 github.com/jtolds/gls v4.20.0+incompatible/go.mod h1:QJZ7F/aHp+rZTRtaJ1ow/lLfFfVYBRgL+9YlvaHOwJU=
-github.com/klauspost/cpuid/v2 v2.2.8 h1:+StwCXwm9PdpiEkPyzBXIy+M9KUb4ODm0Zarf1kS5BM=
-github.com/klauspost/cpuid/v2 v2.2.8/go.mod h1:Lcz8mBdAVJIBVzewtcLocK12l3Y+JytZYpaMropDUws=
+github.com/klauspost/cpuid/v2 v2.2.9 h1:66ze0taIn2H33fBvCkXuv9BmCwDfafmiIVpKV9kKGuY=
+github.com/klauspost/cpuid/v2 v2.2.9/go.mod h1:rqkxqrZ1EhYM9G+hXH7YdowN5R5RGN6NK4QwQ3WMXF8=
 github.com/kr/pretty v0.3.1 h1:flRD4NNwYAUpkphVc1HcthR4KEIFJ65n8Mw5qdRn3LE=
 github.com/kr/pretty v0.3.1/go.mod h1:hoEshYVHaxMs3cyo3Yncou5ZscifuDolrwPKZanG3xk=
 github.com/kr/text v0.2.0 h1:5Nx0Ya0ZqY2ygV366QzturHI13Jq95ApcVaJBhpS+AY=
@@ -36,14 +36,14 @@ github.com/lestrrat-go/httprc v1.0.6 h1:qgmgIRhpvBqexMJjA/PmwSvhNk679oqD1RbovdCG
 github.com/lestrrat-go/httprc v1.0.6/go.mod h1:mwwz3JMTPBjHUkkDv/IGJ39aALInZLrhBp0X7KGUZlo=
 github.com/lestrrat-go/iter v1.0.2 h1:gMXo1q4c2pHmC3dn8LzRhJfP1ceCbgSiT9lUydIzltI=
 github.com/lestrrat-go/iter v1.0.2/go.mod h1:Momfcq3AnRlRjI5b5O8/G5/BvpzrhoFTZcn06fEOPt4=
-github.com/lestrrat-go/jwx/v2 v2.1.1 h1:Y2ltVl8J6izLYFs54BVcpXLv5msSW4o8eXwnzZLI32E=
-github.com/lestrrat-go/jwx/v2 v2.1.1/go.mod h1:4LvZg7oxu6Q5VJwn7Mk/UwooNRnTHUpXBj2C4j3HNx0=
+github.com/lestrrat-go/jwx/v2 v2.1.3 h1:Ud4lb2QuxRClYAmRleF50KrbKIoM1TddXgBrneT5/Jo=
+github.com/lestrrat-go/jwx/v2 v2.1.3/go.mod h1:q6uFgbgZfEmQrfJfrCo90QcQOcXFMfbI/fO0NqRtvZo=
 github.com/lestrrat-go/option v1.0.1 h1:oAzP2fvZGQKWkvHa1/SAcFolBEca1oN+mQ7eooNBEYU=
 github.com/lestrrat-go/option v1.0.1/go.mod h1:5ZHFbivi4xwXxhxY9XHDe2FHo6/Z7WWmtT7T5nBBp3I=
 github.com/libp2p/go-buffer-pool v0.1.0 h1:oK4mSFcQz7cTQIfqbe4MIj9gLW+mnanjyFtc6cdF0Y8=
 github.com/libp2p/go-buffer-pool v0.1.0/go.mod h1:N+vh8gMqimBzdKkSMVuydVDq+UV5QTWy5HSiZacSbPg=
-github.com/libp2p/go-libp2p v0.36.3 h1:NHz30+G7D8Y8YmznrVZZla0ofVANrvBl2c+oARfMeDQ=
-github.com/libp2p/go-libp2p v0.36.3/go.mod h1:4Y5vFyCUiJuluEPmpnKYf6WFx5ViKPUYs/ixe9ANFZ8=
+github.com/libp2p/go-libp2p v0.33.0 h1:yTPSr8sJRbfeEYXyeN8VPVSlTlFjtMUwGDRniwaf/xQ=
+github.com/libp2p/go-libp2p v0.33.0/go.mod h1:RIJFRQVUBKy82dnW7J5f1homqqv6NcsDJAl3e7CRGfE=
 github.com/minio/sha256-simd v1.0.1 h1:6kaan5IFmwTNynnKKpDHe6FWHohJOHhCPchzK49dzMM=
 github.com/minio/sha256-simd v1.0.1/go.mod h1:Pz6AKMiUdngCLpeTL/RJY1M9rUuPMYujV5xJjtbRSN8=
 github.com/mr-tron/base58 v1.2.0 h1:T/HDJBh4ZCPbU39/+c3rRvE0uKBQlU27+QI8LJ4t64o=
@@ -52,8 +52,8 @@ github.com/multiformats/go-base32 v0.1.0 h1:pVx9xoSPqEIQG8o+UbAe7DNi51oej1NtK+aG
 github.com/multiformats/go-base32 v0.1.0/go.mod h1:Kj3tFY6zNr+ABYMqeUNeGvkIC/UYgtWibDcT0rExnbI=
 github.com/multiformats/go-base36 v0.2.0 h1:lFsAbNOGeKtuKozrtBsAkSVhv1p9D0/qedU9rQyccr0=
 github.com/multiformats/go-base36 v0.2.0/go.mod h1:qvnKE++v+2MWCfePClUEjE78Z7P2a1UV0xHgWc0hkp4=
-github.com/multiformats/go-multiaddr v0.13.0 h1:BCBzs61E3AGHcYYTv8dqRH43ZfyrqM8RXVPT8t13tLQ=
-github.com/multiformats/go-multiaddr v0.13.0/go.mod h1:sBXrNzucqkFJhvKOiwwLyqamGa/P5EIXNPLovyhQCII=
+github.com/multiformats/go-multiaddr v0.12.2 h1:9G9sTY/wCYajKa9lyfWPmpZAwe6oV+Wb1zcmMS1HG24=
+github.com/multiformats/go-multiaddr v0.12.2/go.mod h1:GKyaTYjZRdcUhyOetrxTk9z0cW+jA/YrnqTOvKgi44M=
 github.com/multiformats/go-multibase v0.2.0 h1:isdYCVLvksgWlMW9OZRYJEa9pZETFivncJHmHnnd87g=
 github.com/multiformats/go-multibase v0.2.0/go.mod h1:bFBZX4lKCA/2lyOFSAoKH5SS6oPyjtnzK/XTFDPkNuk=
 github.com/multiformats/go-multicodec v0.9.0 h1:pb/dlPnzee/Sxv/j4PmkDRxCOi3hXTz3IbPKOXWJkmg=
@@ -81,25 +81,24 @@ github.com/spaolacci/murmur3 v1.1.0/go.mod h1:JwIasOWyU6f++ZhiEuf87xNszmSA2myDM2
 github.com/stretchr/objx v0.1.0/go.mod h1:HFkY916IF+rwdDfMAkV7OtwuqBVzrE8GR6GFx+wExME=
 github.com/stretchr/testify v1.6.1/go.mod h1:6Fq8oRcR53rry900zMqJjRRixrwX3KX962/h/Wwjteg=
 github.com/stretchr/testify v1.7.1/go.mod h1:6Fq8oRcR53rry900zMqJjRRixrwX3KX962/h/Wwjteg=
-github.com/stretchr/testify v1.9.0 h1:HtqpIVDClZ4nwg75+f6Lvsy/wHu+3BoSGCbBAcpTsTg=
-github.com/stretchr/testify v1.9.0/go.mod h1:r2ic/lqez/lEtzL7wO/rwa5dbSLXVDPFyf8C91i36aY=
+github.com/stretchr/testify v1.10.0 h1:Xv5erBjTwe/5IxqUQTdXv5kgmIvbHo3QQyRwhJsOfJA=
+github.com/stretchr/testify v1.10.0/go.mod h1:r2ic/lqez/lEtzL7wO/rwa5dbSLXVDPFyf8C91i36aY=
 github.com/urfave/cli v1.22.10/go.mod h1:Gos4lmkARVdJ6EkW0WaNv/tZAAMe9V7XWyB60NtXRu0=
 github.com/warpfork/go-wish v0.0.0-20220906213052-39a1cc7a02d0 h1:GDDkbFiaK8jsSDJfjId/PEGEShv6ugrt4kYsC5UIDaQ=
 github.com/warpfork/go-wish v0.0.0-20220906213052-39a1cc7a02d0/go.mod h1:x6AKhvSSexNrVSrViXSHUEbICjmGXhtgABaHIySUSGw=
 golang.org/x/crypto v0.0.0-20190308221718-c2843e01d9a2/go.mod h1:djNgcEr1/C05ACkg1iLfiJU5Ep61QUkGW8qpdssI0+w=
-golang.org/x/crypto v0.25.0 h1:ypSNr+bnYL2YhwoMt2zPxHFmbAN1KZs/njMG3hxUp30=
-golang.org/x/crypto v0.25.0/go.mod h1:T+wALwcMOSE0kXgUAnPAHqTLW+XHgcELELW8VaDgm/M=
-golang.org/x/exp v0.0.0-20240719175910-8a7402abbf56 h1:2dVuKD2vS7b0QIHQbpyTISPd0LeHDbnYEryqj5Q1ug8=
-golang.org/x/exp v0.0.0-20240719175910-8a7402abbf56/go.mod h1:M4RDyNAINzryxdtnbRXRL/OHtkFuWGRjvuhBJpk2IlY=
+golang.org/x/crypto v0.32.0 h1:euUpcYgM8WcP71gNpTqQCn6rC2t6ULUPiOzfWaXVVfc=
+golang.org/x/crypto v0.32.0/go.mod h1:ZnnJkOaASj8g0AjIduWNlq2NRxL0PlBrbKVyZ6V/Ugc=
+golang.org/x/exp v0.0.0-20240213143201-ec583247a57a h1:HinSgX1tJRX3KsL//Gxynpw5CTOAIPhgL4W8PNiIpVE=
+golang.org/x/exp v0.0.0-20240213143201-ec583247a57a/go.mod h1:CxmFvTBINI24O/j8iY7H1xHzx2i4OsyguNBmN/uPtqc=
 golang.org/x/net v0.0.0-20190311183353-d8887717615a/go.mod h1:t9HGtf8HONx5eT2rtn7q6eTqICYqUVnKs3thJo3Qplg=
 golang.org/x/sys v0.0.0-20190215142949-d0b11bdaac8a/go.mod h1:STP8DvDyc/dI5b8T5hshtkjS+E42TnysNCUPdjciGhY=
-golang.org/x/sys v0.5.0/go.mod h1:oPkhp1MJrh7nUepCBck5+mAzfO9JrbApNNgaTdGDITg=
-golang.org/x/sys v0.22.0 h1:RI27ohtqKCnwULzJLqkv897zojh5/DwS/ENaMzUOaWI=
-golang.org/x/sys v0.22.0/go.mod h1:/VUhepiaJMQUp4+oa/7Zr1D23ma6VTLIYjOOTFZPUcA=
+golang.org/x/sys v0.29.0 h1:TPYlXGxvx1MGTn2GiZDhnjPA9wZzZeGKHHmKhHYvgaU=
+golang.org/x/sys v0.29.0/go.mod h1:/VUhepiaJMQUp4+oa/7Zr1D23ma6VTLIYjOOTFZPUcA=
 golang.org/x/text v0.3.0/go.mod h1:NqM8EUOU14njkJ3fqMW+pc6Ldnwhi/IjpwHt7yyuwOQ=
 golang.org/x/tools v0.0.0-20190328211700-ab21143f2384/go.mod h1:LCzVGOaR6xXOjkQ3onu1FJEFr0SW1gC7cKk1uF8kGRs=
-google.golang.org/protobuf v1.34.2 h1:6xV6lTsCfpGD21XK49h7MhtcApnLqkfYgPcdHftf6hg=
-google.golang.org/protobuf v1.34.2/go.mod h1:qYOHts0dSfpeUzUFpOMr/WGzszTmLH+DiWniOlNbLDw=
+google.golang.org/protobuf v1.36.0 h1:mjIs9gYtt56AzC4ZaffQuh88TZurBGhIJMBZGSxNerQ=
+google.golang.org/protobuf v1.36.0/go.mod h1:9fA7Ob0pmnwhb644+1+CVWFRbNajQ6iRojtC/QF5bRE=
 gopkg.in/check.v1 v0.0.0-20161208181325-20d25e280405/go.mod h1:Co6ibVJAznAaIkqp8huTwlJQCZ016jof/cbN4VW5Yz0=
 gopkg.in/check.v1 v1.0.0-20190902080502-41f04d3bba15 h1:YR8cESwS4TdDjEe65xsg0ogRM/Nc3DYOhEAlW+xobZo=
 gopkg.in/check.v1 v1.0.0-20190902080502-41f04d3bba15/go.mod h1:Co6ibVJAznAaIkqp8huTwlJQCZ016jof/cbN4VW5Yz0=

pkg/args/args.go

@@ -0,0 +1,187 @@
+// Package args provides the type that represents the Arguments passed to
+// a command within an invocation.Token as well as a convenient Add method
+// to incrementally build the underlying map.
+package args
+
+import (
+	"errors"
+	"fmt"
+	"iter"
+	"sort"
+	"strings"
+
+	"github.com/ipld/go-ipld-prime"
+	"github.com/ipld/go-ipld-prime/datamodel"
+	"github.com/ipld/go-ipld-prime/fluent/qp"
+	"github.com/ipld/go-ipld-prime/node/basicnode"
+	"github.com/ipld/go-ipld-prime/printer"
+
+	"github.com/ucan-wg/go-ucan/pkg/policy/limits"
+	"github.com/ucan-wg/go-ucan/pkg/policy/literal"
+)
+
+var ErrNotFound = errors.New("key not found in meta")
+
+// Args are the Command's arguments when an invocation Token is processed by the executor.
+// This also serves as a way to construct the underlying IPLD data with minimum allocations
+// and transformations, while hiding the IPLD complexity from the caller.
+type Args struct {
+	// This type must be compatible with the IPLD type represented by the IPLD
+	// schema { String : Any }.
+
+	Keys   []string
+	Values map[string]ipld.Node
+}
+
+// New returns a pointer to an initialized Args value.
+func New() *Args {
+	return &Args{
+		Values: map[string]ipld.Node{},
+	}
+}
+
+// GetNode retrieves a value as a raw IPLD node.
+// Returns ErrNotFound if the given key is missing.
+func (a *Args) GetNode(key string) (ipld.Node, error) {
+	v, ok := a.Values[key]
+	if !ok {
+		return nil, ErrNotFound
+	}
+	return v, nil
+}
+
+// Add inserts a key/value pair in the Args set.
+//
+// Accepted types for val are any CBOR compatible type, or directly IPLD values.
+func (a *Args) Add(key string, val any) error {
+	if _, ok := a.Values[key]; ok {
+		return fmt.Errorf("duplicate key %q", key)
+	}
+
+	node, err := literal.Any(val)
+	if err != nil {
+		return err
+	}
+
+	if err := limits.ValidateIntegerBoundsIPLD(node); err != nil {
+		return fmt.Errorf("value for key %q: %w", key, err)
+	}
+
+	a.Values[key] = node
+	a.Keys = append(a.Keys, key)
+
+	return nil
+}
+
+type Iterator interface {
+	Iter() iter.Seq2[string, ipld.Node]
+}
+
+// Include merges the provided arguments into the existing arguments.
+//
+// If duplicate keys are encountered, the new value is silently dropped
+// without causing an error.
+func (a *Args) Include(other Iterator) {
+	for key, value := range other.Iter() {
+		if _, ok := a.Values[key]; ok {
+			// don't overwrite
+			continue
+		}
+		a.Values[key] = value
+		a.Keys = append(a.Keys, key)
+	}
+}
+
+// Len return the number of arguments.
+func (a *Args) Len() int {
+	return len(a.Keys)
+}
+
+// Iter iterates over the args key/values
+func (a *Args) Iter() iter.Seq2[string, ipld.Node] {
+	return func(yield func(string, ipld.Node) bool) {
+		for _, key := range a.Keys {
+			if !yield(key, a.Values[key]) {
+				return
+			}
+		}
+	}
+}
+
+// ToIPLD wraps an instance of an Args with an ipld.Node.
+func (a *Args) ToIPLD() (ipld.Node, error) {
+	sort.Strings(a.Keys)
+
+	return qp.BuildMap(basicnode.Prototype.Any, int64(len(a.Keys)), func(ma datamodel.MapAssembler) {
+		for _, key := range a.Keys {
+			qp.MapEntry(ma, key, qp.Node(a.Values[key]))
+		}
+	})
+}
+
+// Equals tells if two Args hold the same values.
+func (a *Args) Equals(other *Args) bool {
+	if len(a.Keys) != len(other.Keys) {
+		return false
+	}
+	if len(a.Values) != len(other.Values) {
+		return false
+	}
+	for _, key := range a.Keys {
+		if !ipld.DeepEqual(a.Values[key], other.Values[key]) {
+			return false
+		}
+	}
+	return true
+}
+
+func (a *Args) String() string {
+	sort.Strings(a.Keys)
+
+	buf := strings.Builder{}
+	buf.WriteString("{")
+
+	for _, key := range a.Keys {
+		buf.WriteString("\n\t")
+		buf.WriteString(key)
+		buf.WriteString(": ")
+		buf.WriteString(strings.ReplaceAll(printer.Sprint(a.Values[key]), "\n", "\n\t"))
+		buf.WriteString(",")
+	}
+
+	if len(a.Keys) > 0 {
+		buf.WriteString("\n")
+	}
+	buf.WriteString("}")
+
+	return buf.String()
+}
+
+// ReadOnly returns a read-only version of Args.
+func (a *Args) ReadOnly() ReadOnly {
+	return ReadOnly{args: a}
+}
+
+// Clone makes a deep copy.
+func (a *Args) Clone() *Args {
+	res := &Args{
+		Keys:   make([]string, len(a.Keys)),
+		Values: make(map[string]ipld.Node, len(a.Values)),
+	}
+	copy(res.Keys, a.Keys)
+	for k, v := range a.Values {
+		res.Values[k] = v
+	}
+	return res
+}
+
+// Validate checks that all values in the Args are valid according to UCAN specs
+func (a *Args) Validate() error {
+	for key, value := range a.Values {
+		if err := limits.ValidateIntegerBoundsIPLD(value); err != nil {
+			return fmt.Errorf("value for key %q: %w", key, err)
+		}
+	}
+
+	return nil
+}

pkg/args/args_test.go

@@ -0,0 +1,297 @@
+package args_test
+
+import (
+	"maps"
+	"sync"
+	"testing"
+
+	"github.com/ipfs/go-cid"
+	"github.com/ipld/go-ipld-prime"
+	"github.com/ipld/go-ipld-prime/codec/dagcbor"
+	"github.com/ipld/go-ipld-prime/datamodel"
+	"github.com/ipld/go-ipld-prime/node/basicnode"
+	"github.com/ipld/go-ipld-prime/schema"
+	"github.com/stretchr/testify/assert"
+	"github.com/stretchr/testify/require"
+
+	"github.com/ucan-wg/go-ucan/pkg/args"
+	"github.com/ucan-wg/go-ucan/pkg/policy/limits"
+	"github.com/ucan-wg/go-ucan/pkg/policy/literal"
+)
+
+func TestArgs(t *testing.T) {
+	t.Parallel()
+
+	const (
+		intKey    = "intKey"
+		mapKey    = "mapKey"
+		nilKey    = "nilKey"
+		boolKey   = "boolKey"
+		linkKey   = "linkKey"
+		listKey   = "listKey"
+		nodeKey   = "nodeKey"
+		uintKey   = "uintKey"
+		bytesKey  = "bytesKey"
+		floatKey  = "floatKey"
+		stringKey = "stringKey"
+	)
+
+	const (
+		expIntVal    = int64(-42)
+		expBoolVal   = true
+		expUintVal   = uint(42)
+		expStringVal = "stringVal"
+	)
+
+	var (
+		expMapVal = map[string]string{"keyOne": "valOne", "keyTwo": "valTwo"}
+		// expNilVal = (map[string]string)(nil)
+		expLinkVal  = cid.MustParse("bafzbeigai3eoy2ccc7ybwjfz5r3rdxqrinwi4rwytly24tdbh6yk7zslrm")
+		expListVal  = []string{"elem1", "elem2", "elem3"}
+		expNodeVal  = literal.String("nodeVal")
+		expBytesVal = []byte{0xde, 0xad, 0xbe, 0xef}
+		expFloatVal = 42.0
+	)
+
+	argsIn := args.New()
+
+	for _, a := range []struct {
+		key string
+		val any
+	}{
+		{key: intKey, val: expIntVal},
+		{key: mapKey, val: expMapVal},
+		// {key:  nilKey, val: expNilVal},
+		{key: boolKey, val: expBoolVal},
+		{key: linkKey, val: expLinkVal},
+		{key: listKey, val: expListVal},
+		{key: uintKey, val: expUintVal},
+		{key: nodeKey, val: expNodeVal},
+		{key: bytesKey, val: expBytesVal},
+		{key: floatKey, val: expFloatVal},
+		{key: stringKey, val: expStringVal},
+	} {
+		require.NoError(t, argsIn.Add(a.key, a.val))
+	}
+
+	// Round-trip to DAG-CBOR
+	argsOut := roundTripThroughDAGCBOR(t, argsIn)
+	assert.ElementsMatch(t, argsIn.Keys, argsOut.Keys)
+	assert.Equal(t, argsIn.Values, argsOut.Values)
+
+	actMapVal := map[string]string{}
+	mit := argsOut.Values[mapKey].MapIterator()
+
+	for !mit.Done() {
+		k, v, err := mit.Next()
+		require.NoError(t, err)
+		ks := must(k.AsString())
+		vs := must(v.AsString())
+		actMapVal[ks] = vs
+	}
+
+	actListVal := []string{}
+	lit := argsOut.Values[listKey].ListIterator()
+
+	for !lit.Done() {
+		_, v, err := lit.Next()
+		require.NoError(t, err)
+		vs := must(v.AsString())
+
+		actListVal = append(actListVal, vs)
+	}
+
+	assert.Equal(t, expIntVal, must(argsOut.Values[intKey].AsInt()))
+	assert.Equal(t, expMapVal, actMapVal) // TODO: special accessor
+	// TODO: the nil map comes back empty (but the right type)
+	// assert.Equal(t, expNilVal, actNilVal)
+	assert.Equal(t, expBoolVal, must(argsOut.Values[boolKey].AsBool()))
+	assert.Equal(t, expLinkVal.String(), must(argsOut.Values[linkKey].AsLink()).(datamodel.Link).String()) // TODO: special accessor
+	assert.Equal(t, expListVal, actListVal)                                                                // TODO: special accessor
+	assert.Equal(t, expNodeVal, argsOut.Values[nodeKey])
+	assert.Equal(t, expUintVal, uint(must(argsOut.Values[uintKey].AsInt())))
+	assert.Equal(t, expBytesVal, must(argsOut.Values[bytesKey].AsBytes()))
+	assert.Equal(t, expFloatVal, must(argsOut.Values[floatKey].AsFloat()))
+	assert.Equal(t, expStringVal, must(argsOut.Values[stringKey].AsString()))
+}
+
+func TestArgs_Include(t *testing.T) {
+	t.Parallel()
+
+	argsIn := args.New()
+	require.NoError(t, argsIn.Add("key1", "val1"))
+	require.NoError(t, argsIn.Add("key2", "val2"))
+
+	argsOther := args.New()
+	require.NoError(t, argsOther.Add("key2", "valOther")) // This should not overwrite key2 above
+	require.NoError(t, argsOther.Add("key3", "val3"))
+	require.NoError(t, argsOther.Add("key4", "val4"))
+
+	argsIn.Include(argsOther)
+
+	assert.Len(t, argsIn.Values, 4)
+	assert.Equal(t, "val1", must(argsIn.Values["key1"].AsString()))
+	assert.Equal(t, "val2", must(argsIn.Values["key2"].AsString()))
+	assert.Equal(t, "val3", must(argsIn.Values["key3"].AsString()))
+	assert.Equal(t, "val4", must(argsIn.Values["key4"].AsString()))
+}
+
+func TestIterCloneEquals(t *testing.T) {
+	a := args.New()
+
+	require.NoError(t, a.Add("foo", "bar"))
+	require.NoError(t, a.Add("baz", 1234))
+
+	expected := map[string]ipld.Node{
+		"foo": basicnode.NewString("bar"),
+		"baz": basicnode.NewInt(1234),
+	}
+
+	// args -> iter
+	require.Equal(t, expected, maps.Collect(a.Iter()))
+
+	// readonly -> iter
+	ro := a.ReadOnly()
+	require.Equal(t, expected, maps.Collect(ro.Iter()))
+
+	// args -> clone -> iter
+	clone := a.Clone()
+	require.Equal(t, expected, maps.Collect(clone.Iter()))
+
+	// readonly -> WriteableClone -> iter
+	wclone := ro.WriteableClone()
+	require.Equal(t, expected, maps.Collect(wclone.Iter()))
+
+	require.True(t, a.Equals(wclone))
+	require.True(t, ro.Equals(wclone.ReadOnly()))
+}
+
+func TestInclude(t *testing.T) {
+	a1 := args.New()
+
+	require.NoError(t, a1.Add("samekey", "bar"))
+	require.NoError(t, a1.Add("baz", 1234))
+
+	a2 := args.New()
+
+	require.NoError(t, a2.Add("samekey", "othervalue")) // check no overwrite
+	require.NoError(t, a2.Add("otherkey", 1234))
+
+	a1.Include(a2)
+
+	require.Equal(t, map[string]ipld.Node{
+		"samekey":  basicnode.NewString("bar"),
+		"baz":      basicnode.NewInt(1234),
+		"otherkey": basicnode.NewInt(1234),
+	}, maps.Collect(a1.Iter()))
+}
+
+func TestArgsIntegerBounds(t *testing.T) {
+	t.Parallel()
+
+	tests := []struct {
+		name    string
+		key     string
+		val     int64
+		wantErr string
+	}{
+		{
+			name: "valid int",
+			key:  "valid",
+			val:  42,
+		},
+		{
+			name: "max safe integer",
+			key:  "max",
+			val:  limits.MaxInt53,
+		},
+		{
+			name: "min safe integer",
+			key:  "min",
+			val:  limits.MinInt53,
+		},
+		{
+			name:    "exceeds max safe integer",
+			key:     "tooBig",
+			val:     limits.MaxInt53 + 1,
+			wantErr: "exceeds safe integer bounds",
+		},
+		{
+			name:    "below min safe integer",
+			key:     "tooSmall",
+			val:     limits.MinInt53 - 1,
+			wantErr: "exceeds safe integer bounds",
+		},
+		{
+			name:    "duplicate key",
+			key:     "duplicate",
+			val:     42,
+			wantErr: "duplicate key",
+		},
+	}
+
+	a := args.New()
+	require.NoError(t, a.Add("duplicate", 1)) // tests duplicate key
+
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			err := a.Add(tt.key, tt.val)
+			if tt.wantErr != "" {
+				require.Error(t, err)
+				require.Contains(t, err.Error(), tt.wantErr)
+			} else {
+				require.NoError(t, err)
+				val, err := a.GetNode(tt.key)
+				require.NoError(t, err)
+				i, err := val.AsInt()
+				require.NoError(t, err)
+				require.Equal(t, tt.val, i)
+			}
+		})
+	}
+}
+
+const (
+	argsSchema = "type Args { String : Any }"
+	argsName   = "Args"
+)
+
+var (
+	once      sync.Once
+	ts        *schema.TypeSystem
+	errSchema error
+)
+
+func argsType() schema.Type {
+	once.Do(func() {
+		ts, errSchema = ipld.LoadSchemaBytes([]byte(argsSchema))
+	})
+	if errSchema != nil {
+		panic(errSchema)
+	}
+
+	return ts.TypeByName(argsName)
+}
+
+func roundTripThroughDAGCBOR(t *testing.T, argsIn *args.Args) *args.Args {
+	t.Helper()
+
+	node, err := argsIn.ToIPLD()
+	require.NoError(t, err)
+
+	data, err := ipld.Encode(node, dagcbor.Encode)
+	require.NoError(t, err)
+
+	var argsOut args.Args
+	_, err = ipld.Unmarshal(data, dagcbor.Decode, &argsOut, argsType())
+	require.NoError(t, err)
+
+	return &argsOut
+}
+
+func must[T any](t T, err error) T {
+	if err != nil {
+		panic(err)
+	}
+	return t
+}

pkg/args/builder.go

@@ -0,0 +1,71 @@
+package args
+
+import (
+	"errors"
+
+	"github.com/ipld/go-ipld-prime"
+)
+
+// Builder allows the fluid construction of an Args.
+type Builder struct {
+	args *Args
+	errs error
+}
+
+// NewBuilder returns a Builder which will assemble the Args.
+func NewBuilder() *Builder {
+	return &Builder{
+		args: New(),
+	}
+}
+
+// Add inserts a new key/val into the Args being assembled while collecting
+// any errors caused by duplicate keys.
+func (b *Builder) Add(key string, val any) *Builder {
+	b.errs = errors.Join(b.errs, b.args.Add(key, val))
+
+	return b
+}
+
+// Build returns the assembled Args or an error containing a list of
+// errors encountered while trying to build the Args.
+func (b *Builder) Build() (*Args, error) {
+	if b.errs != nil {
+		return nil, b.errs
+	}
+
+	return b.args, nil
+}
+
+// BuildIPLD is the same as Build except it takes the additional step of
+// converting the Args to an ipld.Node.
+func (b *Builder) BuildIPLD() (ipld.Node, error) {
+	args, err := b.Build()
+	if err != nil {
+		return nil, err
+	}
+
+	return args.ToIPLD()
+}
+
+// MustBuild is the same as Build except it panics if an error occurs.
+func (b *Builder) MustBuild() *Args {
+	args, err := b.Build()
+
+	if err != nil {
+		panic(b.errs)
+	}
+
+	return args
+}
+
+// MustBuildIPLD is the same as BuildIPLD except it panics if an error
+// occurs.
+func (b *Builder) MustBuildIPLD() ipld.Node {
+	node, err := b.BuildIPLD()
+	if err != nil {
+		panic(err)
+	}
+
+	return node
+}

pkg/args/builder_test.go

@@ -0,0 +1,81 @@
+package args_test
+
+import (
+	"testing"
+
+	"github.com/ipld/go-ipld-prime"
+	"github.com/stretchr/testify/assert"
+	"github.com/stretchr/testify/require"
+	"github.com/ucan-wg/go-ucan/pkg/args"
+)
+
+func TestBuilder_XXX(t *testing.T) {
+	t.Parallel()
+
+	const (
+		keyOne = "key1"
+		valOne = "string"
+		keyTwo = "key2"
+		valTwo = 42
+	)
+
+	exp := args.New()
+	exp.Add(keyOne, valOne)
+	exp.Add(keyTwo, valTwo)
+
+	expNode, err := exp.ToIPLD()
+	require.NoError(t, err)
+
+	disjointKeys := args.NewBuilder().
+		Add(keyOne, valOne).
+		Add(keyTwo, valTwo)
+
+	duplicateKeys := args.NewBuilder().
+		Add(keyOne, valOne).
+		Add(keyTwo, valTwo).
+		Add(keyOne, "oh no!")
+
+	t.Run("MustBuild succeeds with disjoint keys", func(t *testing.T) {
+		t.Parallel()
+
+		var act *args.Args
+
+		require.NotPanics(t, func() {
+			act = disjointKeys.MustBuild()
+		})
+		assert.Equal(t, exp, act)
+	})
+
+	t.Run("MustBuild fails with duplicate keys", func(t *testing.T) {
+		t.Parallel()
+
+		var act *args.Args
+
+		require.Panics(t, func() {
+			act = duplicateKeys.MustBuild()
+		})
+		assert.Nil(t, act)
+	})
+
+	t.Run("MustBuildIPLD succeeds with disjoint keys", func(t *testing.T) {
+		t.Parallel()
+
+		var act ipld.Node
+
+		require.NotPanics(t, func() {
+			act = disjointKeys.MustBuildIPLD()
+		})
+		assert.Equal(t, expNode, act)
+	})
+
+	t.Run("MustBuildIPLD fails with duplicate keys", func(t *testing.T) {
+		t.Parallel()
+
+		var act ipld.Node
+
+		require.Panics(t, func() {
+			act = duplicateKeys.MustBuildIPLD()
+		})
+		assert.Nil(t, act)
+	})
+}

pkg/args/readonly.go

@@ -0,0 +1,39 @@
+package args
+
+import (
+	"iter"
+
+	"github.com/ipld/go-ipld-prime"
+)
+
+type ReadOnly struct {
+	args *Args
+}
+
+func (r ReadOnly) GetNode(key string) (ipld.Node, error) {
+	return r.args.GetNode(key)
+}
+
+func (r ReadOnly) Len() int {
+	return r.args.Len()
+}
+
+func (r ReadOnly) Iter() iter.Seq2[string, ipld.Node] {
+	return r.args.Iter()
+}
+
+func (r ReadOnly) ToIPLD() (ipld.Node, error) {
+	return r.args.ToIPLD()
+}
+
+func (r ReadOnly) Equals(other ReadOnly) bool {
+	return r.args.Equals(other.args)
+}
+
+func (r ReadOnly) String() string {
+	return r.args.String()
+}
+
+func (r ReadOnly) WriteableClone() *Args {
+	return r.args.Clone()
+}

pkg/command/command.go

@@ -98,7 +98,34 @@ func (c Command) Join(segments ...string) Command {
 // Segments returns the ordered segments that comprise the Command as a
 // slice of strings.
 func (c Command) Segments() []string {
-	return strings.Split(string(c), separator)
+	if c == separator {
+		return nil
+	}
+	return strings.Split(string(c), separator)[1:]
+}
+
+// Covers returns true if the command is identical or a parent of the given other command.
+func (c Command) Covers(other Command) bool {
+	// fast-path, equivalent to the code below (verified with fuzzing)
+	if !strings.HasPrefix(string(other), string(c)) {
+		return false
+	}
+	return c == separator || len(c) == len(other) || other[len(c)] == separator[0]
+
+	/* -------
+
+	otherSegments := other.Segments()
+	if len(otherSegments) < len(c.Segments()) {
+		return false
+	}
+	for i, s := range c.Segments() {
+		if otherSegments[i] != s {
+			return false
+		}
+	}
+	return true
+
+	*/
 }
 
 // String returns the composed representation the command.  This is also

pkg/command/command_test.go

@@ -73,6 +73,21 @@ func TestJoin(t *testing.T) {
 	require.Equal(t, "/faz/boz/foo/bar", command.MustParse("/faz/boz").Join("foo", "bar").String())
 }
 
+func TestSegments(t *testing.T) {
+	require.Empty(t, command.Top().Segments())
+	require.Equal(t, []string{"foo", "bar", "baz"}, command.MustParse("/foo/bar/baz").Segments())
+}
+
+func TestCovers(t *testing.T) {
+	require.True(t, command.MustParse("/foo/bar/baz").Covers(command.MustParse("/foo/bar/baz")))
+	require.True(t, command.MustParse("/foo/bar").Covers(command.MustParse("/foo/bar/baz")))
+	require.False(t, command.MustParse("/foo/bar/baz").Covers(command.MustParse("/foo/bar")))
+	require.True(t, command.MustParse("/").Covers(command.MustParse("/foo")))
+	require.True(t, command.MustParse("/").Covers(command.MustParse("/foo/bar/baz")))
+	require.False(t, command.MustParse("/foo").Covers(command.MustParse("/foo00")))
+	require.False(t, command.MustParse("/foo/bar").Covers(command.MustParse("/foo/bar00")))
+}
+
 type testcase struct {
 	name string
 	inp  string

pkg/container/SPEC.md

@@ -0,0 +1,109 @@
+# UCAN container Specification v0.1.0
+
+## Editors
+
+* [Michael Muré], [Consensys]
+
+## Authors
+
+* [Michael Muré], [Consensys]
+* [Hugo Dias]
+
+## Language
+
+The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and "OPTIONAL" in this document are to be interpreted as described in [BCP 14] when, and only when, they appear in all capitals, as shown here.
+
+# 0 Abstract
+
+[User-Controlled Authorization Network (UCAN)][UCAN] is a trustless, secure, local-first, user-originated authorization and revocation scheme. This document describes a container format for transmitting one or more UCAN tokens as bytes, regardless of the transport.
+
+# 1 Introduction
+
+The UCAN spec itself is transport agnostic. This specification describes how to transfer one or more [UCAN] tokens bundled together, regardless of the transport.
+
+# 2 Container format
+
+## 2.1 Inner structure
+
+UCAN tokens, regardless of their kind ([Delegation], [Invocation], [Revocation], [Promise]) MUST be first signed and serialized into DAG-CBOR bytes according to their respective specification. As the token's CID is not part of the serialized container, any CID returned by this operation is to be ignored.
+
+All the tokens' bytes MUST be assembled in a [CBOR] array. The ordering of tokens in the array MUST NOT matter. This array SHOULD NOT have duplicate entries.
+
+That array is then inserted as the value under the `ctn-v1` string key, in a CBOR map. There MUST NOT be other keys.
+
+For clarity, the CBOR shape is given below:
+
+```json
+{
+  "ctn-v1": [
+    <token1 bytes>,
+    <token2 bytes>,
+    <token3 bytes>,
+  ]
+}
+```
+
+## 2.2 Serialisation
+
+To serialize the container into bytes, the inner CBOR structure MUST then be serialized into bytes according to the CBOR specification. The resulting bytes MAY be compressed by a supported algorithm, then MAY be encoded with a supported base encoding.
+
+The following compression algorithms are REQUIRED to be supported:
+- [GZIP]
+
+The following base encoding combinations are REQUIRED to be supported:
+- base64, standard alphabet, padding
+- base64, URL alphabet, no padding
+
+The CBOR bytes MUST be prepended by a single byte header to indicate the selection combination of base encoding and compression. This header value MUST be set according to the following table:
+
+| Header as hex | Header as ASCII | Base encoding           | Compression    |
+|---------------|-----------------|-------------------------|----------------|
+| 0x40          | @               | raw bytes               | no compression | 
+| 0x42          | B               | base64 std padding      | no compression | 
+| 0x43          | C               | base64 url (no padding) | no compression | 
+| 0x4D          | M               | raw bytes               | gzip           | 
+| 0x4F          | O               | base64 std padding      | gzip           | 
+| 0x50          | P               | base64 url (no padding) | gzip           | 
+
+For clarity, the resulting serialisation is in the form of `<header byte><cbor bytes, optionally compressed, optionally encoded>`.
+
+# 3 FAQ
+
+## 3.1 Why not include the UCAN CIDs?
+
+Several attacks are possible if UCAN tokens aren't validated. If CIDs aren't validated, at least two attacks are possible: [privilege escalation] and [cache poisoning], as UCAN delegation proofs depends on a correct hash-linked structure.
+
+By not including the CID in the container, the recipient is forced to hash (and thus validate) the CIDs for each token. If presented with a claimed CID paired with the token bytes, implementers could ignore CID validation, breaking a core part of the proof chain security model. Hash functions are very fast on a couple kilobytes of data so the overhead is still very low. It also significantly reduces the size of the container.
+
+## 3.2 Why compress? Why not always compress?
+
+Compression is a relatively demanding operation. As such, using it is a tradeoff between size on the wire and CPU/memory usage, both when writing and reading a container. The transport itself can make compression worthwhile or not: for example, HTTP/2 and HTTP/3 headers are already compressed, but HTTP/1 headers are not. This being highly contextual, the choice is left to the final implementer.
+
+# 4 Implementation recommendations
+
+## 4.1 Dissociate reader and writer
+
+While it is tempting to write a single implementation to read and write a container, it is RECOMMENDED to separate the implementation into a reader and a writer. The writer can simply accept arbitrary tokens as bytes, while the reader provides a read-only view with convenient access functions.
+
+# 5 Acknowledgments
+
+Many thanks to all the [Fission] team and in particular to [Brooklyn Zelenka] for creating and pushing [UCAN] and other critical pieces like [WNFS], and generally being awesome and supportive people.
+
+<!-- External Links -->
+
+[BCP 14]: https://www.rfc-editor.org/info/bcp14
+[Brooklyn Zelenka]: https://github.com/expede
+[CBOR]: https://www.rfc-editor.org/rfc/rfc8949.html
+[Consensys]: https://consensys.io/
+[Delegation]: https://github.com/ucan-wg/delegation/tree/v1_ipld
+[Fission]: https://fission.codes
+[GZIP]: https://datatracker.ietf.org/doc/html/rfc1952
+[Hugo Dias]: https://github.com/hugomrdias
+[Invocation]: https://github.com/ucan-wg/invocation
+[Michael Muré]: https://github.com/MichaelMure/
+[Promise]: https://github.com/ucan-wg/promise/tree/v1-rc1
+[Revocation]: https://github.com/ucan-wg/revocation/tree/first-draft
+[UCAN]: https://github.com/ucan-wg/spec
+[WNFS]: https://github.com/wnfs-wg
+[cache poisoning]: https://en.wikipedia.org/wiki/Cache_poisoning
+[privilede escalation]: https://en.wikipedia.org/wiki/Privilege_escalation

pkg/container/car_test.go

@@ -40,6 +40,13 @@ func TestCarRoundTrip(t *testing.T) {
 }
 
 func FuzzCarRoundTrip(f *testing.F) {
+	// Note: this fuzzing is somewhat broken.
+	// After some time, the fuzzer discover that a varint can be serialized in different
+	// ways that lead to the same integer value. This means that the CAR format can have
+	// multiple legal binary representation for the exact same data, which is what we are
+	// trying to detect here. Ideally, the format would be stricter, but that's how things
+	// are.
+
 	example, err := os.ReadFile("testdata/sample-v1.car")
 	require.NoError(f, err)
 

pkg/container/containertest/Base64StdPaddingGzipped

@@ -0,0 +1 @@
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

pkg/container/containertest/Base64URLGzipped

@@ -0,0 +1 @@
+PH4sIAAAAAAAA_5zWa5cUxR3HcVcRiejmuCII3siKwgnubnd1dVW1eIS5rzM9w8zs3HZETFd19_T07PTcZ2cH1KMgoB41YgIo3nM0G1GCRhCRiILIEaIhIEo0Bi9c9ewaFfEazYMd8iCPdvIGvk8-p_71e1RnZaujyt_e2_LQLYk5Fbb1QefFR9-_5LzWO59-9PfWoWV_nN_f177z06eH31j13Je8-Wpk35bTccKjtV_22MRfnz9DufuSg8Ntn02KzZtw83sLxj-mGE441FIoVZhidal9qTl8J9fJdRRZJz_IlIpaI2pavTKjDVxZR_5MQXa4aFIFgr-gMCrrOTWUqWNajNZERzin0GLRz7IxsTcfAgnGsqrRpedyXVQpMq2Wn5K68dmLWLpU-p9msRbQ-usuHEsGorZK0BbwxWzxvCdrhDK2vL23UMCRTM0RlStVxPK5vpsXMaWvj3Vee90i5Wq9s6r0VbRTWalC__-smtXKyu8MERNOwJSZkCACeAFgzkC6xGkYAhOLqkJEiBXJkJAuCUBUTMIA4KEgAEWzchbT5DXHfxwc7LiqNnPmRwdHgBa8NO6jDQ9uvW6wa7DHYetfP3DxO4s7JhybLa1YcerUV-Yae7aDww_P2_zjvH9euWqOOW3yjBWtO2__bKzLvfnR_enEpmaBMtFuy4qEsgrlqRMpPm86mql6apjI4V63V_bFgl5WT-USpQhDowVK2amiFmM8tEUsiRJcCeowHM9AvVQreLGE83LMkcBBI99dAE0ANZNtAGFewJjwkilBJPG8TphoKEQhmihKpsgBXuIVhXEGRRQpRGAmhzkRqIpOaQNo4afuoTWTj60cfjw5fQQoxy98ZPGmF3YsWLJo8voJ587Y9-X38geyLBq_nHXZIy9fPun5m1pebqVzv7J-NuaM08XEzYl3v3kmtfuCr2Yc-VAa3vtxS7NAnpKSKsBEzVaMphWdFB0kgNSEgHpwiPe7a0qaxYtVG_SVq_7RAhkey-asYmfUZ1XKMbGSr-Vo1UZ60rZyNV6Uy8l8MY_iES1ic0abAGom2wCCEqcLVFRNpEKBaghAaCBJUYgKOVNVGMQCUyXRQBqFTJWwKQkIIoZFQW8AvZV64bRDez_6flYbbmu8oDa_euu2yJB9w1vX3uO-YrZvobj2yK07V7-1YebjrRcgbsvS4fiyJ9_gpx4KvT5n_A7PTz-cqF_asuuaoTFnn2N-bbU2CaSHi0bJlrEi3kyh6NFrgqOu59VKOJ2t9Xj4sllT4wXqJdFQfzI2aiBvIGSG_Zls2IsDSdKblRV3QlQz2X7Z2evudVBk16QIM1yiCZsBaiLbAOIEnROQppu8AjgKiKqIhgQVwDQCTCKJkqCIBIqGpoicCilvcoxDWJewcPLE3TD0fHzb0y_BrtRd2gjQN3fd--36ju_CYzuV8adcsOeA95UvVv-09N1t05_bN7DllouWTN-18r4nTm-9Y8uZ2L02fj1XLizHlzyfrZ-x65Pt503b0uyJs0oDhpWuSh4vwFpJjlcDciKRCbtQTzmvxkWrKIWCUQm51FomO1ogKyMLyXSPx0xHxKrixwFT7a9XgzUUTuedXgDi8XKmgGJmJOwMNQHUTLYBhERGkE6YCTXEYYAYxxuE5xGnCbopAkWjAtCgbhCMKAUQmQqkvA4wJaQBpNyhPfDyK9Ijs-yOv40ArTv_hoMtSbB12NjtzD1Ef35ow47k_D3frn41f-2LX6YmdTxzzba3t180_7XFV5m-fz304tj2Td-t7Nx_oblszv7ctI2Hmz1xhayl1myOkhEOxUt2S_S4shFvMI7dIbseyPa4AlalJ8q6g2KhGBktUJGVfQEaSsXtsK7EnXnC6zIP84ZHrYUyGR9vcxXj9lwuaIvG7E0ANZM9-QcBHkNCNFMFEKhYFTRiSBoUOV0RTE3DKmWMCJKhijzgeJWakgoIwyLUuAZQSlq-Y177mBOSHt49AjRF-PBAe9d1H3ffcvyZczrHLAhP9X3jC5y797YFa-mNxYl_evDqo4fu_8NZh3d88un1R1f_5cfBf8_76p3tv_psyooll_k-nj2mWaC6b8BCmVrCytYjIFZKF1wytmUFKdijVuoCLIdrBV8dk3AxbIwWqJRAkpyRMnkY9ReLcipX8PR3u6RcrheykFINGCCc7-lJ25LMpjUB1Ez25IljDHFYpCYUiUYR4yVkUMKYIEiSiTDBSFcRgAajPAOU6ibjmShBToOwAXRf-6V31zceuXHdjHV9I0D7Jn7wgXzr4TVX_-PYw_mpLatO69_qW7R1Q-m8o9OcsGP2rM_f3lM_3n0_-aL18zWHV-eHzkik9r4_LriMt16a98Tm889sdiTASDqRwFLW3evj6_mU6i96cqInGEY4Ea0F1brlsPUXJSlCrcpogfRCzGll1YKRsqXrWEuVajq21wK5buKv5FxOV7wQy4Wz5Wwg3NRIaCbbABKopoi6BkymSSrTRCpSQ8UqEEQBmkTTBQp0VcSGBgAvYaiZCgQMUiz89wXdVtm7cNtjqvLmb5ZtHAHq2vfX9Uem2q-ZXTzw3oub0ruemj52f29hwuWeZ2_6_qylidcO5d9p3310-_wptTV3Dv1WXZzbuLsNDU2-dzDy7Sf84MxxTQKZAxWi5wO0Agci0WTOnStHklUpbPaHSi7JcsV9UbvH6_IHzHTVNeqRwLtlj6rV_T3ZehxGex2KLA3EXX4XhNmaGZdj-VjCRgy37HA4mhkJTWQbQBImhOkcbyIeQA1oiOcNBVBEdBWYlOc0IgBAREPnBYoABSavUAI0RhFuAM22T_nzs8NTTyz94YFVI0Bze_9-4utz3dvfW5B7fXL7uJWvr-1rO-uG5evusY_jlk-ynvzheOfE5IFIt4ieunAfO3bK-CWuX2w-0HbQP_fDi-8Y2NPsitNYLCfr2YLGEhrwg7LNoL3ZWKLSAzwDxNvNV_OA1L0oFVdToz5xuURswBupyoo7Ggua8Vg8kIjV5TLvcyCUDJsV7PXKuglTehn5mwBqJnvyBSEd6qpKTV5HCEOeU4mBCJSwpImmIkBd4BRGoUEUHUlMQ6amQVVVJB2CBpBwxRsH-9-cvnYnOfvd_wQAAP__hMJ751MQAAA

pkg/container/containertest/containertest.go

@@ -0,0 +1,21 @@
+package containertest
+
+import _ "embed"
+
+//go:embed Base64StdPadding
+var Base64StdPadding string
+
+//go:embed Base64StdPaddingGzipped
+var Base64StdPaddingGzipped string
+
+//go:embed Base64URL
+var Base64URL string
+
+//go:embed Base64URLGzipped
+var Base64URLGzipped string
+
+//go:embed Bytes
+var Bytes []byte
+
+//go:embed BytesGzipped
+var BytesGzipped []byte

pkg/container/packaging.go

@@ -0,0 +1,118 @@
+package container
+
+import (
+	"compress/gzip"
+	"encoding/base64"
+	"errors"
+	"fmt"
+	"io"
+)
+
+const containerVersionTag = "ctn-v1"
+
+type header byte
+
+const (
+	headerRawBytes             = header(0x40)
+	headerBase64StdPadding     = header(0x42)
+	headerBase64URL            = header(0x43)
+	headerRawBytesGzip         = header(0x4D)
+	headerBase64StdPaddingGzip = header(0x4F)
+	headerBase64URLGzip        = header(0x50)
+)
+
+func (h header) encoder(w io.Writer) *payloadWriter {
+	res := &payloadWriter{rawWriter: w, writer: w, header: h}
+
+	switch h {
+	case headerBase64StdPadding, headerBase64StdPaddingGzip:
+		b64Writer := base64.NewEncoder(base64.StdEncoding, res.writer)
+		res.writer = b64Writer
+		res.closers = append([]io.Closer{b64Writer}, res.closers...)
+	case headerBase64URL, headerBase64URLGzip:
+		b64Writer := base64.NewEncoder(base64.RawURLEncoding, res.writer)
+		res.writer = b64Writer
+		res.closers = append([]io.Closer{b64Writer}, res.closers...)
+	}
+
+	switch h {
+	case headerRawBytesGzip, headerBase64StdPaddingGzip, headerBase64URLGzip:
+		gzipWriter := gzip.NewWriter(res.writer)
+		res.writer = gzipWriter
+		res.closers = append([]io.Closer{gzipWriter}, res.closers...)
+	}
+
+	return res
+}
+
+func payloadDecoder(r io.Reader) (io.Reader, error) {
+	headerBuf := make([]byte, 1)
+	_, err := r.Read(headerBuf)
+	if err != nil {
+		return nil, err
+	}
+	h := header(headerBuf[0])
+
+	switch h {
+	case headerRawBytes,
+		headerBase64StdPadding,
+		headerBase64URL,
+		headerRawBytesGzip,
+		headerBase64StdPaddingGzip,
+		headerBase64URLGzip:
+	default:
+		return nil, fmt.Errorf("unknown container header")
+	}
+
+	switch h {
+	case headerBase64StdPadding, headerBase64StdPaddingGzip:
+		r = base64.NewDecoder(base64.StdEncoding, r)
+	case headerBase64URL, headerBase64URLGzip:
+		r = base64.NewDecoder(base64.RawURLEncoding, r)
+	}
+
+	switch h {
+	case headerRawBytesGzip, headerBase64StdPaddingGzip, headerBase64URLGzip:
+		gzipReader, err := gzip.NewReader(r)
+		if err != nil {
+			return nil, err
+		}
+		r = gzipReader
+	}
+
+	return r, nil
+}
+
+var _ io.WriteCloser = &payloadWriter{}
+
+// payloadWriter is tasked with two things:
+// - prepend the header byte
+// - call Close() on all the underlying io.Writer
+type payloadWriter struct {
+	rawWriter   io.Writer
+	writer      io.Writer
+	header      header
+	headerWrote bool
+	closers     []io.Closer
+}
+
+func (w *payloadWriter) Write(p []byte) (n int, err error) {
+	if !w.headerWrote {
+		_, err := w.rawWriter.Write([]byte{byte(w.header)})
+		if err != nil {
+			return 0, err
+		}
+		w.headerWrote = true
+	}
+	return w.writer.Write(p)
+}
+
+func (w *payloadWriter) Close() error {
+	var errs error
+	for _, closer := range w.closers {
+		if err := closer.Close(); err != nil {
+			errs = errors.Join(errs, err)
+		}
+	}
+	return errs
+}

pkg/container/reader.go

@@ -1,14 +1,15 @@
 package container
 
 import (
-	"encoding/base64"
+	"bytes"
 	"fmt"
 	"io"
 	"iter"
+	"strings"
 
 	"github.com/ipfs/go-cid"
 	"github.com/ipld/go-ipld-prime"
-	"github.com/ipld/go-ipld-prime/codec/dagcbor"
+	"github.com/ipld/go-ipld-prime/codec/cbor"
 	"github.com/ipld/go-ipld-prime/datamodel"
 
 	"github.com/ucan-wg/go-ucan/token"
@@ -17,96 +18,67 @@ import (
 )
 
 var ErrNotFound = fmt.Errorf("not found")
+var ErrMultipleInvocations = fmt.Errorf("multiple invocations")
 
 // Reader is a token container reader. It exposes the tokens conveniently decoded.
-type Reader map[cid.Cid]token.Token
+type Reader map[cid.Cid]bundle
 
-// GetToken returns an arbitrary decoded token, from its CID.
-// If not found, ErrNotFound is returned.
-func (ctn Reader) GetToken(cid cid.Cid) (token.Token, error) {
-	tkn, ok := ctn[cid]
-	if !ok {
-		return nil, ErrNotFound
-	}
-	return tkn, nil
+type bundle struct {
+	sealed []byte
+	token  token.Token
 }
 
-// GetDelegation is the same as GetToken but only return a delegation.Token, with the right type.
-func (ctn Reader) GetDelegation(cid cid.Cid) (*delegation.Token, error) {
-	tkn, err := ctn.GetToken(cid)
-	if err != nil {
-		return nil, err
-	}
-	if tkn, ok := tkn.(*delegation.Token); ok {
-		return tkn, nil
-	}
-	return nil, fmt.Errorf("not a delegation token")
+// FromBytes decodes a container from a []byte
+func FromBytes(data []byte) (Reader, error) {
+	return FromReader(bytes.NewReader(data))
 }
 
-// GetAllDelegations returns all the delegation.Token in the container.
-func (ctn Reader) GetAllDelegations() iter.Seq2[cid.Cid, *delegation.Token] {
-	return func(yield func(cid.Cid, *delegation.Token) bool) {
-		for c, t := range ctn {
-			if t, ok := t.(*delegation.Token); ok {
-				if !yield(c, t) {
-					return
-				}
-			}
-		}
-	}
+// FromString decodes a container from a string
+func FromString(s string) (Reader, error) {
+	return FromReader(strings.NewReader(s))
 }
 
-// GetInvocation returns the first found invocation.Token.
-// If none are found, ErrNotFound is returned.
-func (ctn Reader) GetInvocation() (*invocation.Token, error) {
-	for _, t := range ctn {
-		if inv, ok := t.(*invocation.Token); ok {
-			return inv, nil
-		}
-	}
-	return nil, ErrNotFound
-}
-
-func FromCar(r io.Reader) (Reader, error) {
-	_, it, err := readCar(r)
+// FromReader decodes a container from an io.Reader.
+func FromReader(r io.Reader) (Reader, error) {
+	payload, err := payloadDecoder(r)
 	if err != nil {
 		return nil, err
 	}
 
-	ctn := make(Reader)
-
-	for block, err := range it {
-		if err != nil {
-			return nil, err
-		}
-
-		err = ctn.addToken(block.data)
-		if err != nil {
-			return nil, err
-		}
-	}
-
-	return ctn, nil
-}
-
-func FromCarBase64(r io.Reader) (Reader, error) {
-	return FromCar(base64.NewDecoder(base64.StdEncoding, r))
-}
-
-func FromCbor(r io.Reader) (Reader, error) {
-	n, err := ipld.DecodeStreaming(r, dagcbor.Decode)
+	n, err := ipld.DecodeStreaming(payload, cbor.Decode)
 	if err != nil {
 		return nil, err
 	}
-	if n.Kind() != datamodel.Kind_List {
-		return nil, fmt.Errorf("not a list")
+	if n.Kind() != datamodel.Kind_Map {
+		return nil, fmt.Errorf("invalid container format: expected map")
+	}
+	if n.Length() != 1 {
+		return nil, fmt.Errorf("invalid container format: expected single version key")
 	}
 
-	ctn := make(Reader, n.Length())
+	// get the first (and only) key-value pair
+	it := n.MapIterator()
+	key, tokensNode, err := it.Next()
+	if err != nil {
+		return nil, err
+	}
 
-	it := n.ListIterator()
-	for !it.Done() {
-		_, val, err := it.Next()
+	version, err := key.AsString()
+	if err != nil {
+		return nil, fmt.Errorf("invalid container format: version must be string")
+	}
+	if version != containerVersionTag {
+		return nil, fmt.Errorf("unsupported container version: %s", version)
+	}
+
+	if tokensNode.Kind() != datamodel.Kind_List {
+		return nil, fmt.Errorf("invalid container format: tokens must be a list")
+	}
+
+	ctn := make(Reader, tokensNode.Length())
+	it2 := tokensNode.ListIterator()
+	for !it2.Done() {
+		_, val, err := it2.Next()
 		if err != nil {
 			return nil, err
 		}
@@ -122,8 +94,105 @@ func FromCbor(r io.Reader) (Reader, error) {
 	return ctn, nil
 }
 
-func FromCborBase64(r io.Reader) (Reader, error) {
-	return FromCbor(base64.NewDecoder(base64.StdEncoding, r))
+// GetToken returns an arbitrary decoded token, from its CID.
+// If not found, ErrNotFound is returned.
+func (ctn Reader) GetToken(cid cid.Cid) (token.Token, error) {
+	bndl, ok := ctn[cid]
+	if !ok {
+		return nil, ErrNotFound
+	}
+	return bndl.token, nil
+}
+
+// GetSealed returns an arbitrary sealed token, from its CID.
+// If not found, ErrNotFound is returned.
+func (ctn Reader) GetSealed(cid cid.Cid) ([]byte, error) {
+	bndl, ok := ctn[cid]
+	if !ok {
+		return nil, ErrNotFound
+	}
+	return bndl.sealed, nil
+}
+
+// GetAllTokens return all the tokens in the container.
+func (ctn Reader) GetAllTokens() iter.Seq[token.Bundle] {
+	return func(yield func(token.Bundle) bool) {
+		for c, bndl := range ctn {
+			if !yield(token.Bundle{
+				Cid:     c,
+				Decoded: bndl.token,
+				Sealed:  bndl.sealed,
+			}) {
+				return
+			}
+		}
+	}
+}
+
+// GetDelegation is the same as GetToken but only return a delegation.Token, with the right type.
+// If not found, delegation.ErrDelegationNotFound is returned.
+func (ctn Reader) GetDelegation(cid cid.Cid) (*delegation.Token, error) {
+	tkn, err := ctn.GetToken(cid)
+	if err != nil { // only ErrNotFound expected
+		return nil, delegation.ErrDelegationNotFound
+	}
+	if tkn, ok := tkn.(*delegation.Token); ok {
+		return tkn, nil
+	}
+	return nil, delegation.ErrDelegationNotFound
+}
+
+// GetAllDelegations returns all the delegation.Token in the container.
+func (ctn Reader) GetAllDelegations() iter.Seq[delegation.Bundle] {
+	return func(yield func(delegation.Bundle) bool) {
+		for c, bndl := range ctn {
+			if t, ok := bndl.token.(*delegation.Token); ok {
+				if !yield(delegation.Bundle{
+					Cid:     c,
+					Decoded: t,
+					Sealed:  bndl.sealed,
+				}) {
+					return
+				}
+			}
+		}
+	}
+}
+
+// GetInvocation returns a single invocation.Token.
+// If none are found, ErrNotFound is returned.
+// If more than one invocation exists, ErrMultipleInvocations is returned.
+func (ctn Reader) GetInvocation() (*invocation.Token, error) {
+	var res *invocation.Token
+	for _, bndl := range ctn {
+		if inv, ok := bndl.token.(*invocation.Token); ok {
+			if res != nil {
+				return nil, ErrMultipleInvocations
+			}
+			res = inv
+		}
+	}
+	if res == nil {
+		return nil, ErrNotFound
+	}
+	return res, nil
+}
+
+// GetAllInvocations returns all the invocation.Token in the container.
+func (ctn Reader) GetAllInvocations() iter.Seq[invocation.Bundle] {
+	return func(yield func(invocation.Bundle) bool) {
+		for c, bndl := range ctn {
+			if t, ok := bndl.token.(*invocation.Token); ok {
+				if !yield(invocation.Bundle{
+					Cid:     c,
+					Decoded: t,
+					Sealed:  bndl.sealed,
+				}) {
+					return
+				}
+			}
+		}
+	}
 }
 
 func (ctn Reader) addToken(data []byte) error {
@@ -131,6 +200,19 @@ func (ctn Reader) addToken(data []byte) error {
 	if err != nil {
 		return err
 	}
-	ctn[c] = tkn
+	ctn[c] = bundle{
+		sealed: data,
+		token:  tkn,
+	}
 	return nil
 }
+
+// ToWriter convert a container Reader into a Writer.
+// Most likely, you only want to use this in tests for convenience.
+func (ctn Reader) ToWriter() Writer {
+	writer := NewWriter()
+	for _, bndl := range ctn {
+		writer.AddSealed(bndl.sealed)
+	}
+	return writer
+}

pkg/container/serial_test.go

@@ -22,14 +22,22 @@ import (
 
 func TestContainerRoundTrip(t *testing.T) {
 	for _, tc := range []struct {
-		name   string
-		writer func(ctn Writer, w io.Writer) error
-		reader func(io.Reader) (Reader, error)
+		name           string
+		expectedHeader header
+		writer         any
 	}{
-		{"car", Writer.ToCar, FromCar},
-		{"carBase64", Writer.ToCarBase64, FromCarBase64},
-		{"cbor", Writer.ToCbor, FromCbor},
-		{"cborBase64", Writer.ToCborBase64, FromCborBase64},
+		{"Bytes", headerRawBytes, Writer.ToBytes},
+		{"BytesWriter", headerRawBytes, Writer.ToBytesWriter},
+		{"BytesGzipped", headerRawBytesGzip, Writer.ToBytesGzipped},
+		{"BytesGzippedWriter", headerRawBytesGzip, Writer.ToBytesGzippedWriter},
+		{"Base64StdPadding", headerBase64StdPadding, Writer.ToBase64StdPadding},
+		{"Base64StdPaddingWriter", headerBase64StdPadding, Writer.ToBase64StdPaddingWriter},
+		{"Base64StdPaddingGzipped", headerBase64StdPaddingGzip, Writer.ToBase64StdPaddingGzipped},
+		{"Base64StdPaddingGzippedWriter", headerBase64StdPaddingGzip, Writer.ToBase64StdPaddingGzippedWriter},
+		{"Base64URL", headerBase64URL, Writer.ToBase64URL},
+		{"Base64URLWriter", headerBase64URL, Writer.ToBase64URLWriter},
+		{"Base64URLGzipped", headerBase64URLGzip, Writer.ToBase64URLGzipped},
+		{"Base64URLGzipWriter", headerBase64URLGzip, Writer.ToBase64URLGzipWriter},
 	} {
 		t.Run(tc.name, func(t *testing.T) {
 			tokens := make(map[cid.Cid]*delegation.Token)
@@ -39,21 +47,53 @@ func TestContainerRoundTrip(t *testing.T) {
 
 			for i := 0; i < 10; i++ {
 				dlg, c, data := randToken()
-				writer.AddSealed(c, data)
+				writer.AddSealed(data)
 				tokens[c] = dlg
 				dataSize += len(data)
 			}
 
-			buf := bytes.NewBuffer(nil)
+			var reader Reader
+			var serialLen int
 
-			err := tc.writer(writer, buf)
-			require.NoError(t, err)
+			switch fn := tc.writer.(type) {
+			case func(ctn Writer, w io.Writer) error:
+				buf := bytes.NewBuffer(nil)
+				err := fn(writer, buf)
+				require.NoError(t, err)
+				serialLen = buf.Len()
 
-			t.Logf("data size %d", dataSize)
-			t.Logf("container overhead: %d%%, %d bytes", int(float32(buf.Len()-dataSize)/float32(dataSize)*100.0), buf.Len()-dataSize)
+				h, err := buf.ReadByte()
+				require.NoError(t, err)
+				require.Equal(t, byte(tc.expectedHeader), h)
+				err = buf.UnreadByte()
+				require.NoError(t, err)
 
-			reader, err := tc.reader(bytes.NewReader(buf.Bytes()))
-			require.NoError(t, err)
+				reader, err = FromReader(bytes.NewReader(buf.Bytes()))
+				require.NoError(t, err)
+
+			case func(ctn Writer) ([]byte, error):
+				b, err := fn(writer)
+				require.NoError(t, err)
+				serialLen = len(b)
+
+				require.Equal(t, byte(tc.expectedHeader), b[0])
+
+				reader, err = FromBytes(b)
+				require.NoError(t, err)
+
+			case func(ctn Writer) (string, error):
+				s, err := fn(writer)
+				require.NoError(t, err)
+				serialLen = len(s)
+
+				require.Equal(t, byte(tc.expectedHeader), s[0])
+
+				reader, err = FromString(s)
+				require.NoError(t, err)
+			}
+
+			t.Logf("data size %d, container size %d, overhead: %d%%, %d bytes",
+				dataSize, serialLen, int(float32(serialLen-dataSize)/float32(dataSize)*100.0), serialLen-dataSize)
 
 			for c, dlg := range tokens {
 				tknRead, err := reader.GetToken(c)
@@ -98,16 +138,18 @@ func BenchmarkContainerSerialisation(b *testing.B) {
 		writer func(ctn Writer, w io.Writer) error
 		reader func(io.Reader) (Reader, error)
 	}{
-		{"car", Writer.ToCar, FromCar},
-		{"carBase64", Writer.ToCarBase64, FromCarBase64},
-		{"cbor", Writer.ToCbor, FromCbor},
-		{"cborBase64", Writer.ToCborBase64, FromCborBase64},
+		{"Bytes", Writer.ToBytesWriter, FromReader},
+		{"BytesGzipped", Writer.ToBytesGzippedWriter, FromReader},
+		{"Base64StdPadding", Writer.ToBase64StdPaddingWriter, FromReader},
+		{"Base64StdPaddingGzipped", Writer.ToBase64StdPaddingGzippedWriter, FromReader},
+		{"Base64URL", Writer.ToBase64URLWriter, FromReader},
+		{"Base64URLGzip", Writer.ToBase64URLGzipWriter, FromReader},
 	} {
 		writer := NewWriter()
 
 		for i := 0; i < 10; i++ {
-			_, c, data := randToken()
-			writer.AddSealed(c, data)
+			_, _, data := randToken()
+			writer.AddSealed(data)
 		}
 
 		buf := bytes.NewBuffer(nil)
@@ -160,13 +202,12 @@ func randToken() (*delegation.Token, cid.Cid, []byte) {
 
 	opts := []delegation.Option{
 		delegation.WithExpiration(time.Now().Add(time.Hour)),
-		delegation.WithSubject(iss),
 	}
 	for i := 0; i < 3; i++ {
 		opts = append(opts, delegation.WithMeta(randomString(8), randomString(10)))
 	}
 
-	t, err := delegation.New(priv, aud, cmd, pol, opts...)
+	t, err := delegation.Root(iss, aud, cmd, pol, opts...)
 	if err != nil {
 		panic(err)
 	}
@@ -176,3 +217,29 @@ func randToken() (*delegation.Token, cid.Cid, []byte) {
 	}
 	return t, c, b
 }
+
+func FuzzContainerRead(f *testing.F) {
+	// Generate a corpus
+	for tokenCount := 0; tokenCount < 10; tokenCount++ {
+		writer := NewWriter()
+		for i := 0; i < tokenCount; i++ {
+			_, _, data := randToken()
+			writer.AddSealed(data)
+		}
+		data, err := writer.ToBytes()
+		require.NoError(f, err)
+
+		f.Add(data)
+	}
+
+	f.Fuzz(func(t *testing.T, data []byte) {
+		start := time.Now()
+
+		// search for panics
+		_, _ = FromBytes(data)
+
+		if time.Since(start) > 100*time.Millisecond {
+			panic("too long")
+		}
+	})
+}

pkg/container/writer.go

@@ -1,61 +1,139 @@
 package container
 
 import (
-	"encoding/base64"
+	"bytes"
 	"io"
 
-	"github.com/ipfs/go-cid"
 	"github.com/ipld/go-ipld-prime"
-	"github.com/ipld/go-ipld-prime/codec/dagcbor"
+	"github.com/ipld/go-ipld-prime/codec/cbor"
 	"github.com/ipld/go-ipld-prime/datamodel"
 	"github.com/ipld/go-ipld-prime/fluent/qp"
 	"github.com/ipld/go-ipld-prime/node/basicnode"
 )
 
-// TODO: should we have a multibase to wrap the cbor? but there is no reader/write in go-multibase :-(
-
 // Writer is a token container writer. It provides a convenient way to aggregate and serialize tokens together.
-type Writer map[cid.Cid][]byte
+type Writer map[string]struct{}
 
 func NewWriter() Writer {
 	return make(Writer)
 }
 
 // AddSealed includes a "sealed" token (serialized with a ToSealed* function) in the container.
-func (ctn Writer) AddSealed(cid cid.Cid, data []byte) {
-	ctn[cid] = data
+func (ctn Writer) AddSealed(data []byte) {
+	ctn[string(data)] = struct{}{}
 }
 
-func (ctn Writer) ToCar(w io.Writer) error {
-	return writeCar(w, nil, func(yield func(carBlock, error) bool) {
-		for c, bytes := range ctn {
-			if !yield(carBlock{c: c, data: bytes}, nil) {
-				return
+// ToBytes encode the container into raw bytes.
+func (ctn Writer) ToBytes() ([]byte, error) {
+	return ctn.toBytes(headerRawBytes)
+}
+
+// ToBytesWriter is the same as ToBytes, but with an io.Writer.
+func (ctn Writer) ToBytesWriter(w io.Writer) error {
+	return ctn.toWriter(headerRawBytes, w)
+}
+
+// ToBytesGzipped encode the container into gzipped bytes.
+func (ctn Writer) ToBytesGzipped() ([]byte, error) {
+	return ctn.toBytes(headerRawBytesGzip)
+}
+
+// ToBytesGzippedWriter is the same as ToBytesGzipped, but with an io.Writer.
+func (ctn Writer) ToBytesGzippedWriter(w io.Writer) error {
+	return ctn.toWriter(headerRawBytesGzip, w)
+}
+
+// ToBase64StdPadding encode the container into a base64 string, with standard encoding and padding.
+func (ctn Writer) ToBase64StdPadding() (string, error) {
+	return ctn.toString(headerBase64StdPadding)
+}
+
+// ToBase64StdPaddingWriter is the same as ToBase64StdPadding, but with an io.Writer.
+func (ctn Writer) ToBase64StdPaddingWriter(w io.Writer) error {
+	return ctn.toWriter(headerBase64StdPadding, w)
+}
+
+// ToBase64StdPaddingGzipped encode the container into a pre-gzipped base64 string, with standard encoding and padding.
+func (ctn Writer) ToBase64StdPaddingGzipped() (string, error) {
+	return ctn.toString(headerBase64StdPaddingGzip)
+}
+
+// ToBase64StdPaddingGzippedWriter is the same as ToBase64StdPaddingGzipped, but with an io.Writer.
+func (ctn Writer) ToBase64StdPaddingGzippedWriter(w io.Writer) error {
+	return ctn.toWriter(headerBase64StdPaddingGzip, w)
+}
+
+// ToBase64URL encode the container into base64 string, with URL-safe encoding and no padding.
+func (ctn Writer) ToBase64URL() (string, error) {
+	return ctn.toString(headerBase64URL)
+}
+
+// ToBase64URLWriter is the same as ToBase64URL, but with an io.Writer.
+func (ctn Writer) ToBase64URLWriter(w io.Writer) error {
+	return ctn.toWriter(headerBase64URL, w)
+}
+
+// ToBase64URL encode the container into pre-gzipped base64 string, with URL-safe encoding and no padding.
+func (ctn Writer) ToBase64URLGzipped() (string, error) {
+	return ctn.toString(headerBase64URLGzip)
+}
+
+// ToBase64URLWriter is the same as ToBase64URL, but with an io.Writer.
+func (ctn Writer) ToBase64URLGzipWriter(w io.Writer) error {
+	return ctn.toWriter(headerBase64URLGzip, w)
+}
+
+func (ctn Writer) toBytes(header header) ([]byte, error) {
+	var buf bytes.Buffer
+	err := ctn.toWriter(header, &buf)
+	if err != nil {
+		return nil, err
+	}
+	return buf.Bytes(), nil
+}
+
+func (ctn Writer) toString(header header) (string, error) {
+	var buf bytes.Buffer
+	err := ctn.toWriter(header, &buf)
+	if err != nil {
+		return "", err
+	}
+	return buf.String(), nil
+}
+
+func (ctn Writer) toWriter(header header, w io.Writer) (err error) {
+	encoder := header.encoder(w)
+
+	defer func() {
+		err = encoder.Close()
+	}()
+	node, err := qp.BuildMap(basicnode.Prototype.Any, 1, func(ma datamodel.MapAssembler) {
+		qp.MapEntry(ma, containerVersionTag, qp.List(int64(len(ctn)), func(la datamodel.ListAssembler) {
+			for data, _ := range ctn {
+				qp.ListEntry(la, qp.Bytes([]byte(data)))
 			}
-		}
-	})
-}
-
-func (ctn Writer) ToCarBase64(w io.Writer) error {
-	w2 := base64.NewEncoder(base64.StdEncoding, w)
-	defer w2.Close()
-	return ctn.ToCar(w2)
-}
-
-func (ctn Writer) ToCbor(w io.Writer) error {
-	node, err := qp.BuildList(basicnode.Prototype.Any, int64(len(ctn)), func(la datamodel.ListAssembler) {
-		for _, bytes := range ctn {
-			qp.ListEntry(la, qp.Bytes(bytes))
-		}
+		}))
 	})
 	if err != nil {
 		return err
 	}
-	return ipld.EncodeStreaming(w, node, dagcbor.Encode)
+
+	return ipld.EncodeStreaming(encoder, node, cbor.Encode)
 }
 
-func (ctn Writer) ToCborBase64(w io.Writer) error {
-	w2 := base64.NewEncoder(base64.StdEncoding, w)
-	defer w2.Close()
-	return ctn.ToCbor(w2)
+// ToReader convert a container Writer into a Reader.
+// Most likely, you only want to use this in tests for convenience.
+// This is not optimized and can panic.
+func (ctn Writer) ToReader() Reader {
+	data, err := ctn.ToBytes()
+	if err != nil {
+		panic(err)
+	}
+
+	reader, err := FromBytes(data)
+	if err != nil {
+		panic(err)
+	}
+
+	return reader
 }

pkg/container/writer_test.go

@@ -0,0 +1,18 @@
+package container
+
+import (
+	"testing"
+
+	"github.com/stretchr/testify/require"
+)
+
+func TestWriterDedup(t *testing.T) {
+	ctn := NewWriter()
+
+	_, _, sealed := randToken()
+	ctn.AddSealed(sealed)
+	require.Len(t, ctn, 1)
+
+	ctn.AddSealed(sealed)
+	require.Len(t, ctn, 1)
+}

pkg/meta/meta.go

@@ -1,24 +1,30 @@
 package meta
 
 import (
+	"errors"
 	"fmt"
-	"reflect"
+	"iter"
+	"sort"
 	"strings"
 
 	"github.com/ipld/go-ipld-prime"
-	"github.com/ipld/go-ipld-prime/datamodel"
-	"github.com/ipld/go-ipld-prime/node/basicnode"
 	"github.com/ipld/go-ipld-prime/printer"
+
+	"github.com/ucan-wg/go-ucan/pkg/policy/literal"
+	"github.com/ucan-wg/go-ucan/pkg/secretbox"
 )
 
-var ErrUnsupported = fmt.Errorf("failure adding unsupported type to meta")
+var ErrNotFound = errors.New("key not found in meta")
 
-var ErrNotFound = fmt.Errorf("key-value not found in meta")
+var ErrNotEncryptable = errors.New("value of this type cannot be encrypted")
 
 // Meta is a container for meta key-value pairs in a UCAN token.
-// This also serves as a way to construct the underlying IPLD data with minimum allocations and transformations,
-// while hiding the IPLD complexity from the caller.
+// This also serves as a way to construct the underlying IPLD data with minimum allocations
+// and transformations, while hiding the IPLD complexity from the caller.
 type Meta struct {
+	// This type must be compatible with the IPLD type represented by the IPLD
+	// schema { String : Any }.
+
 	Keys   []string
 	Values map[string]ipld.Node
 }
@@ -50,6 +56,21 @@ func (m *Meta) GetString(key string) (string, error) {
 	return v.AsString()
 }
 
+// GetEncryptedString decorates GetString and decrypt its output with the given symmetric encryption key.
+func (m *Meta) GetEncryptedString(key string, encryptionKey []byte) (string, error) {
+	v, err := m.GetBytes(key)
+	if err != nil {
+		return "", err
+	}
+
+	decrypted, err := secretbox.DecryptStringWithKey(v, encryptionKey)
+	if err != nil {
+		return "", err
+	}
+
+	return string(decrypted), nil
+}
+
 // GetInt64 retrieves a value as an int64.
 // Returns ErrNotFound if the given key is missing.
 // Returns datamodel.ErrWrongKind if the value has the wrong type.
@@ -83,9 +104,23 @@ func (m *Meta) GetBytes(key string) ([]byte, error) {
 	return v.AsBytes()
 }
 
+// GetEncryptedBytes decorates GetBytes and decrypt its output with the given symmetric encryption key.
+func (m *Meta) GetEncryptedBytes(key string, encryptionKey []byte) ([]byte, error) {
+	v, err := m.GetBytes(key)
+	if err != nil {
+		return nil, err
+	}
+
+	decrypted, err := secretbox.DecryptStringWithKey(v, encryptionKey)
+	if err != nil {
+		return nil, err
+	}
+
+	return decrypted, nil
+}
+
 // GetNode retrieves a value as a raw IPLD node.
 // Returns ErrNotFound if the given key is missing.
-// Returns datamodel.ErrWrongKind if the value has the wrong type.
 func (m *Meta) GetNode(key string) (ipld.Node, error) {
 	v, ok := m.Values[key]
 	if !ok {
@@ -95,35 +130,84 @@ func (m *Meta) GetNode(key string) (ipld.Node, error) {
 }
 
 // Add adds a key/value pair in the meta set.
-// Accepted types for the value are: bool, string, int, int32, int64, []byte,
-// and ipld.Node.
+// Accepted types for val are any CBOR compatible type, or directly IPLD values.
 func (m *Meta) Add(key string, val any) error {
-	switch val := val.(type) {
-	case bool:
-		m.Values[key] = basicnode.NewBool(val)
-	case string:
-		m.Values[key] = basicnode.NewString(val)
-	case int:
-		m.Values[key] = basicnode.NewInt(int64(val))
-	case int32:
-		m.Values[key] = basicnode.NewInt(int64(val))
-	case int64:
-		m.Values[key] = basicnode.NewInt(val)
-	case float32:
-		m.Values[key] = basicnode.NewFloat(float64(val))
-	case float64:
-		m.Values[key] = basicnode.NewFloat(val)
-	case []byte:
-		m.Values[key] = basicnode.NewBytes(val)
-	case datamodel.Node:
-		m.Values[key] = val
-	default:
-		return fmt.Errorf("%w: %s", ErrUnsupported, fqtn(val))
+	if _, ok := m.Values[key]; ok {
+		return fmt.Errorf("duplicate key %q", key)
 	}
+
+	node, err := literal.Any(val)
+	if err != nil {
+		return err
+	}
+
 	m.Keys = append(m.Keys, key)
+	m.Values[key] = node
+
 	return nil
 }
 
+// AddEncrypted adds a key/value pair in the meta set.
+// The value is encrypted with the given encryptionKey.
+// Accepted types for the value are: string, []byte.
+// The ciphertext will be 40 bytes larger than the plaintext due to encryption overhead.
+func (m *Meta) AddEncrypted(key string, val any, encryptionKey []byte) error {
+	var encrypted []byte
+	var err error
+
+	switch val := val.(type) {
+	case string:
+		encrypted, err = secretbox.EncryptWithKey([]byte(val), encryptionKey)
+		if err != nil {
+			return err
+		}
+	case []byte:
+		encrypted, err = secretbox.EncryptWithKey(val, encryptionKey)
+		if err != nil {
+			return err
+		}
+	default:
+		return ErrNotEncryptable
+	}
+
+	return m.Add(key, encrypted)
+}
+
+type Iterator interface {
+	Iter() iter.Seq2[string, ipld.Node]
+}
+
+// Include merges the provided meta into the existing one.
+//
+// If duplicate keys are encountered, the new value is silently dropped
+// without causing an error.
+func (m *Meta) Include(other Iterator) {
+	for key, value := range other.Iter() {
+		if _, ok := m.Values[key]; ok {
+			// don't overwrite
+			continue
+		}
+		m.Values[key] = value
+		m.Keys = append(m.Keys, key)
+	}
+}
+
+// Len returns the number of key/values.
+func (m *Meta) Len() int {
+	return len(m.Values)
+}
+
+// Iter iterates over the meta key/values
+func (m *Meta) Iter() iter.Seq2[string, ipld.Node] {
+	return func(yield func(string, ipld.Node) bool) {
+		for _, key := range m.Keys {
+			if !yield(key, m.Values[key]) {
+				return
+			}
+		}
+	}
+}
+
 // Equals tells if two Meta hold the same key/values.
 func (m *Meta) Equals(other *Meta) bool {
 	if len(m.Keys) != len(other.Keys) {
@@ -141,37 +225,41 @@ func (m *Meta) Equals(other *Meta) bool {
 }
 
 func (m *Meta) String() string {
+	sort.Strings(m.Keys)
+
 	buf := strings.Builder{}
 	buf.WriteString("{")
 
-	var i int
 	for key, node := range m.Values {
-		if i > 0 {
-			buf.WriteString(", ")
-		}
-		i++
+		buf.WriteString("\n\t")
 		buf.WriteString(key)
-		buf.WriteString(":")
-		buf.WriteString(printer.Sprint(node))
+		buf.WriteString(": ")
+		buf.WriteString(strings.ReplaceAll(printer.Sprint(node), "\n", "\n\t"))
+		buf.WriteString(",")
 	}
 
+	if len(m.Values) > 0 {
+		buf.WriteString("\n")
+	}
 	buf.WriteString("}")
+
 	return buf.String()
 }
 
 // ReadOnly returns a read-only version of Meta.
 func (m *Meta) ReadOnly() ReadOnly {
-	return ReadOnly{m: m}
+	return ReadOnly{meta: m}
 }
 
-func fqtn(val any) string {
-	var name string
-
-	t := reflect.TypeOf(val)
-	for t.Kind() == reflect.Pointer {
-		name += "*"
-		t = t.Elem()
+// Clone makes a deep copy.
+func (m *Meta) Clone() *Meta {
+	res := &Meta{
+		Keys:   make([]string, len(m.Keys)),
+		Values: make(map[string]ipld.Node, len(m.Values)),
 	}
-
-	return name + t.PkgPath() + "." + t.Name()
+	copy(res.Keys, m.Keys)
+	for k, v := range m.Values {
+		res.Values[k] = v
+	}
+	return res
 }

pkg/meta/meta_test.go

@@ -1,10 +1,13 @@
 package meta_test
 
 import (
+	"crypto/rand"
+	"maps"
 	"testing"
 
+	"github.com/ipld/go-ipld-prime"
+	"github.com/ipld/go-ipld-prime/node/basicnode"
 	"github.com/stretchr/testify/require"
-	"gotest.tools/v3/assert"
 
 	"github.com/ucan-wg/go-ucan/pkg/meta"
 )
@@ -14,11 +17,114 @@ func TestMeta_Add(t *testing.T) {
 
 	type Unsupported struct{}
 
-	t.Run("error if not primative or Node", func(t *testing.T) {
+	t.Run("error if not primitive or Node", func(t *testing.T) {
 		t.Parallel()
 
 		err := (&meta.Meta{}).Add("invalid", &Unsupported{})
-		require.ErrorIs(t, err, meta.ErrUnsupported)
-		assert.ErrorContains(t, err, "*github.com/ucan-wg/go-ucan/pkg/meta_test.Unsupported")
+		require.Error(t, err)
+	})
+
+	t.Run("encrypted meta", func(t *testing.T) {
+		t.Parallel()
+
+		key := make([]byte, 32)
+		_, err := rand.Read(key)
+		require.NoError(t, err)
+
+		m := meta.NewMeta()
+
+		// string encryption
+		err = m.AddEncrypted("secret", "hello world", key)
+		require.NoError(t, err)
+
+		_, err = m.GetString("secret")
+		require.Error(t, err) // the ciphertext is saved as []byte instead of string
+
+		decrypted, err := m.GetEncryptedString("secret", key)
+		require.NoError(t, err)
+		require.Equal(t, "hello world", decrypted)
+
+		// bytes encryption
+		originalBytes := make([]byte, 128)
+		_, err = rand.Read(originalBytes)
+		require.NoError(t, err)
+		err = m.AddEncrypted("secret-bytes", originalBytes, key)
+		require.NoError(t, err)
+
+		encryptedBytes, err := m.GetBytes("secret-bytes")
+		require.NoError(t, err)
+		require.NotEqual(t, originalBytes, encryptedBytes)
+
+		decryptedBytes, err := m.GetEncryptedBytes("secret-bytes", key)
+		require.NoError(t, err)
+		require.Equal(t, originalBytes, decryptedBytes)
+
+		// error cases
+		t.Run("error on unsupported type", func(t *testing.T) {
+			err := m.AddEncrypted("invalid", 123, key)
+			require.ErrorIs(t, err, meta.ErrNotEncryptable)
+		})
+
+		t.Run("error on invalid key size", func(t *testing.T) {
+			err := m.AddEncrypted("invalid", "test", []byte("short-key"))
+			require.Error(t, err)
+			require.Contains(t, err.Error(), "invalid key size")
+		})
+
+		t.Run("error on nil key", func(t *testing.T) {
+			err := m.AddEncrypted("invalid", "test", nil)
+			require.Error(t, err)
+			require.Contains(t, err.Error(), "encryption key is required")
+		})
 	})
 }
+
+func TestIterCloneEquals(t *testing.T) {
+	m := meta.NewMeta()
+
+	require.NoError(t, m.Add("foo", "bar"))
+	require.NoError(t, m.Add("baz", 1234))
+
+	expected := map[string]ipld.Node{
+		"foo": basicnode.NewString("bar"),
+		"baz": basicnode.NewInt(1234),
+	}
+
+	// meta -> iter
+	require.Equal(t, expected, maps.Collect(m.Iter()))
+
+	// readonly -> iter
+	ro := m.ReadOnly()
+	require.Equal(t, expected, maps.Collect(ro.Iter()))
+
+	// meta -> clone -> iter
+	clone := m.Clone()
+	require.Equal(t, expected, maps.Collect(clone.Iter()))
+
+	// readonly -> WriteableClone -> iter
+	wclone := ro.WriteableClone()
+	require.Equal(t, expected, maps.Collect(wclone.Iter()))
+
+	require.True(t, m.Equals(wclone))
+	require.True(t, ro.Equals(wclone.ReadOnly()))
+}
+
+func TestInclude(t *testing.T) {
+	m1 := meta.NewMeta()
+
+	require.NoError(t, m1.Add("samekey", "bar"))
+	require.NoError(t, m1.Add("baz", 1234))
+
+	m2 := meta.NewMeta()
+
+	require.NoError(t, m2.Add("samekey", "othervalue")) // check no overwrite
+	require.NoError(t, m2.Add("otherkey", 1234))
+
+	m1.Include(m2)
+
+	require.Equal(t, map[string]ipld.Node{
+		"samekey":  basicnode.NewString("bar"),
+		"baz":      basicnode.NewInt(1234),
+		"otherkey": basicnode.NewInt(1234),
+	}, maps.Collect(m1.Iter()))
+}

pkg/meta/readonly.go

@@ -1,42 +1,64 @@
 package meta
 
 import (
+	"iter"
+
 	"github.com/ipld/go-ipld-prime"
 )
 
 // ReadOnly wraps a Meta into a read-only facade.
 type ReadOnly struct {
-	m *Meta
+	meta *Meta
 }
 
 func (r ReadOnly) GetBool(key string) (bool, error) {
-	return r.m.GetBool(key)
+	return r.meta.GetBool(key)
 }
 
 func (r ReadOnly) GetString(key string) (string, error) {
-	return r.m.GetString(key)
+	return r.meta.GetString(key)
+}
+
+func (r ReadOnly) GetEncryptedString(key string, encryptionKey []byte) (string, error) {
+	return r.meta.GetEncryptedString(key, encryptionKey)
 }
 
 func (r ReadOnly) GetInt64(key string) (int64, error) {
-	return r.m.GetInt64(key)
+	return r.meta.GetInt64(key)
 }
 
 func (r ReadOnly) GetFloat64(key string) (float64, error) {
-	return r.m.GetFloat64(key)
+	return r.meta.GetFloat64(key)
 }
 
 func (r ReadOnly) GetBytes(key string) ([]byte, error) {
-	return r.m.GetBytes(key)
+	return r.meta.GetBytes(key)
+}
+
+func (r ReadOnly) GetEncryptedBytes(key string, encryptionKey []byte) ([]byte, error) {
+	return r.meta.GetEncryptedBytes(key, encryptionKey)
 }
 
 func (r ReadOnly) GetNode(key string) (ipld.Node, error) {
-	return r.m.GetNode(key)
+	return r.meta.GetNode(key)
+}
+
+func (r ReadOnly) Len() int {
+	return r.meta.Len()
+}
+
+func (r ReadOnly) Iter() iter.Seq2[string, ipld.Node] {
+	return r.meta.Iter()
 }
 
 func (r ReadOnly) Equals(other ReadOnly) bool {
-	return r.m.Equals(other.m)
+	return r.meta.Equals(other.meta)
 }
 
 func (r ReadOnly) String() string {
-	return r.m.String()
+	return r.meta.String()
+}
+
+func (r ReadOnly) WriteableClone() *Meta {
+	return r.meta.Clone()
 }

pkg/policy/ipld.go

@@ -9,10 +9,15 @@ import (
 	"github.com/ipld/go-ipld-prime/must"
 	"github.com/ipld/go-ipld-prime/node/basicnode"
 
+	"github.com/ucan-wg/go-ucan/pkg/policy/limits"
 	"github.com/ucan-wg/go-ucan/pkg/policy/selector"
 )
 
 func FromIPLD(node datamodel.Node) (Policy, error) {
+	if err := limits.ValidateIntegerBoundsIPLD(node); err != nil {
+		return nil, fmt.Errorf("policy contains integer values outside safe bounds: %w", err)
+	}
+
 	return statementsFromIPLD("/", node)
 }
 
@@ -76,7 +81,7 @@ func statementFromIPLD(path string, node datamodel.Node) (Statement, error) {
 		}
 	case 3:
 		switch op {
-		case KindEqual, KindLessThan, KindLessThanOrEqual, KindGreaterThan, KindGreaterThanOrEqual:
+		case KindEqual, KindNotEqual, KindLessThan, KindLessThanOrEqual, KindGreaterThan, KindGreaterThanOrEqual:
 			sel, err := arg2AsSelector(op)
 			if err != nil {
 				return nil, err

pkg/policy/ipld_test.go

@@ -21,10 +21,31 @@ func TestIpldRoundTrip(t *testing.T) {
   ]
 ]`
 
+	// must contain all the operators
+	const allOps = `
+[
+  ["and", [
+    ["==", ".foo1", ".bar1"],
+    ["!=", ".foo2", ".bar2"]
+  ]],
+  ["or", [
+    [">", ".foo5", 5.2],
+    [">=", ".foo6", 6.2]
+  ]],
+  ["not", ["like", ".foo7", "*@example.com"]],
+  ["all", ".foo8",
+    ["<", ".foo3", 3]
+  ],
+  ["any", ".foo9",
+    ["<=", ".foo4", 4]
+  ]
+]`
+
 	for _, tc := range []struct {
 		name, dagJsonStr string
 	}{
 		{"illustrativeExample", illustrativeExample},
+		{"allOps", allOps},
 	} {
 		nodes, err := ipld.Decode([]byte(tc.dagJsonStr), dagjson.Decode)
 		require.NoError(t, err)

pkg/policy/limits/int.go

@@ -0,0 +1,49 @@
+package limits
+
+import (
+	"fmt"
+
+	"github.com/ipld/go-ipld-prime"
+	"github.com/ipld/go-ipld-prime/must"
+)
+
+const (
+	// MaxInt53 represents the maximum safe integer in JavaScript (2^53 - 1)
+	MaxInt53 int64 = 9007199254740991
+	// MinInt53 represents the minimum safe integer in JavaScript (-2^53 + 1)
+	MinInt53 int64 = -9007199254740991
+)
+
+func ValidateIntegerBoundsIPLD(node ipld.Node) error {
+	switch node.Kind() {
+	case ipld.Kind_Int:
+		val := must.Int(node)
+		if val > MaxInt53 || val < MinInt53 {
+			return fmt.Errorf("integer value %d exceeds safe bounds", val)
+		}
+	case ipld.Kind_List:
+		it := node.ListIterator()
+		for !it.Done() {
+			_, v, err := it.Next()
+			if err != nil {
+				return err
+			}
+			if err := ValidateIntegerBoundsIPLD(v); err != nil {
+				return err
+			}
+		}
+	case ipld.Kind_Map:
+		it := node.MapIterator()
+		for !it.Done() {
+			_, v, err := it.Next()
+			if err != nil {
+				return err
+			}
+			if err := ValidateIntegerBoundsIPLD(v); err != nil {
+				return err
+			}
+		}
+	}
+
+	return nil
+}

pkg/policy/limits/int_test.go

@@ -0,0 +1,82 @@
+package limits
+
+import (
+	"testing"
+
+	"github.com/ipld/go-ipld-prime/datamodel"
+	"github.com/ipld/go-ipld-prime/fluent/qp"
+	"github.com/ipld/go-ipld-prime/node/basicnode"
+	"github.com/stretchr/testify/require"
+)
+
+func TestValidateIntegerBoundsIPLD(t *testing.T) {
+	buildMap := func() datamodel.Node {
+		nb := basicnode.Prototype.Any.NewBuilder()
+		qp.Map(1, func(ma datamodel.MapAssembler) {
+			qp.MapEntry(ma, "foo", qp.Int(MaxInt53+1))
+		})(nb)
+		return nb.Build()
+	}
+
+	buildList := func() datamodel.Node {
+		nb := basicnode.Prototype.Any.NewBuilder()
+		qp.List(1, func(la datamodel.ListAssembler) {
+			qp.ListEntry(la, qp.Int(MinInt53-1))
+		})(nb)
+		return nb.Build()
+	}
+
+	tests := []struct {
+		name    string
+		input   datamodel.Node
+		wantErr bool
+	}{
+		{
+			name:    "valid int",
+			input:   basicnode.NewInt(42),
+			wantErr: false,
+		},
+		{
+			name:    "max safe int",
+			input:   basicnode.NewInt(MaxInt53),
+			wantErr: false,
+		},
+		{
+			name:    "min safe int",
+			input:   basicnode.NewInt(MinInt53),
+			wantErr: false,
+		},
+		{
+			name:    "above MaxInt53",
+			input:   basicnode.NewInt(MaxInt53 + 1),
+			wantErr: true,
+		},
+		{
+			name:    "below MinInt53",
+			input:   basicnode.NewInt(MinInt53 - 1),
+			wantErr: true,
+		},
+		{
+			name:    "nested map with invalid int",
+			input:   buildMap(),
+			wantErr: true,
+		},
+		{
+			name:    "nested list with invalid int",
+			input:   buildList(),
+			wantErr: true,
+		},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			err := ValidateIntegerBoundsIPLD(tt.input)
+			if tt.wantErr {
+				require.Error(t, err)
+				require.Contains(t, err.Error(), "exceeds safe bounds")
+			} else {
+				require.NoError(t, err)
+			}
+		})
+	}
+}

pkg/policy/literal/literal.go

@@ -4,6 +4,7 @@ package literal
 import (
 	"fmt"
 	"reflect"
+	"sort"
 
 	"github.com/ipfs/go-cid"
 	"github.com/ipld/go-ipld-prime"
@@ -11,6 +12,8 @@ import (
 	"github.com/ipld/go-ipld-prime/fluent/qp"
 	cidlink "github.com/ipld/go-ipld-prime/linking/cid"
 	"github.com/ipld/go-ipld-prime/node/basicnode"
+
+	"github.com/ucan-wg/go-ucan/pkg/policy/limits"
 )
 
 var Bool = basicnode.NewBool
@@ -33,8 +36,14 @@ func Null() ipld.Node {
 // Map creates an IPLD node from a map[string]any
 func Map[T any](m map[string]T) (ipld.Node, error) {
 	return qp.BuildMap(basicnode.Prototype.Any, int64(len(m)), func(ma datamodel.MapAssembler) {
-		for k, v := range m {
-			qp.MapEntry(ma, k, anyAssemble(v))
+		// deterministic iteration
+		keys := make([]string, 0, len(m))
+		for key := range m {
+			keys = append(keys, key)
+		}
+		sort.Strings(keys)
+		for _, key := range keys {
+			qp.MapEntry(ma, key, anyAssemble(m[key]))
 		}
 	})
 }
@@ -48,6 +57,72 @@ func List[T any](l []T) (ipld.Node, error) {
 	})
 }
 
+// Any creates an IPLD node from any value
+// If possible, use another dedicated function for your type for performance.
+func Any(v any) (res ipld.Node, err error) {
+	// some fast path
+	switch val := v.(type) {
+	case bool:
+		return basicnode.NewBool(val), nil
+	case string:
+		return basicnode.NewString(val), nil
+	case int:
+		i := int64(val)
+		if i > limits.MaxInt53 || i < limits.MinInt53 {
+			return nil, fmt.Errorf("integer value %d exceeds safe integer bounds", i)
+		}
+		return basicnode.NewInt(i), nil
+	case int8:
+		return basicnode.NewInt(int64(val)), nil
+	case int16:
+		return basicnode.NewInt(int64(val)), nil
+	case int32:
+		return basicnode.NewInt(int64(val)), nil
+	case int64:
+		if val > limits.MaxInt53 || val < limits.MinInt53 {
+			return nil, fmt.Errorf("integer value %d exceeds safe integer bounds", val)
+		}
+		return basicnode.NewInt(val), nil
+	case uint:
+		return basicnode.NewInt(int64(val)), nil
+	case uint8:
+		return basicnode.NewInt(int64(val)), nil
+	case uint16:
+		return basicnode.NewInt(int64(val)), nil
+	case uint32:
+		return basicnode.NewInt(int64(val)), nil
+	case uint64:
+		if val > uint64(limits.MaxInt53) {
+			return nil, fmt.Errorf("unsigned integer value %d exceeds safe integer bounds", val)
+		}
+		return basicnode.NewInt(int64(val)), nil
+	case float32:
+		return basicnode.NewFloat(float64(val)), nil
+	case float64:
+		return basicnode.NewFloat(val), nil
+	case []byte:
+		return basicnode.NewBytes(val), nil
+	case datamodel.Node:
+		return val, nil
+	case cid.Cid:
+		return LinkCid(val), nil
+	default:
+	}
+
+	builder := basicnode.Prototype__Any{}.NewBuilder()
+
+	defer func() {
+		if r := recover(); r != nil {
+			err = fmt.Errorf("%v", r)
+			res = nil
+		}
+	}()
+
+	anyAssemble(v)(builder)
+
+	return builder.Build(), nil
+}
+
 func anyAssemble(val any) qp.Assemble {
 	var rt reflect.Type
 	var rv reflect.Value
@@ -90,22 +165,39 @@ func anyAssemble(val any) qp.Assemble {
 		if rt.Key().Kind() != reflect.String {
 			break
 		}
-		it := rv.MapRange()
+		// deterministic iteration
+		keys := rv.MapKeys()
+		sort.Slice(keys, func(i, j int) bool {
+			return keys[i].String() < keys[j].String()
+		})
 		return qp.Map(int64(rv.Len()), func(ma datamodel.MapAssembler) {
-			for it.Next() {
-				qp.MapEntry(ma, it.Key().String(), anyAssemble(it.Value()))
+			for _, key := range keys {
+				qp.MapEntry(ma, key.String(), anyAssemble(rv.MapIndex(key)))
 			}
 		})
 	case reflect.Bool:
 		return qp.Bool(rv.Bool())
 	case reflect.Int, reflect.Int8, reflect.Int16, reflect.Int32, reflect.Int64:
-		return qp.Int(rv.Int())
+		i := rv.Int()
+		if i > limits.MaxInt53 || i < limits.MinInt53 {
+			panic(fmt.Sprintf("integer %d exceeds safe bounds", i))
+		}
+		return qp.Int(i)
 	case reflect.Uint, reflect.Uint8, reflect.Uint16, reflect.Uint32, reflect.Uint64:
-		return qp.Int(int64(rv.Uint()))
+		u := rv.Uint()
+		if u > uint64(limits.MaxInt53) {
+			panic(fmt.Sprintf("unsigned integer %d exceeds safe bounds", u))
+		}
+		return qp.Int(int64(u))
 	case reflect.Float32, reflect.Float64:
 		return qp.Float(rv.Float())
 	case reflect.String:
 		return qp.String(rv.String())
+	case reflect.Struct:
+		if rt == reflect.TypeOf(cid.Cid{}) {
+			c := rv.Interface().(cid.Cid)
+			return qp.Link(cidlink.Link{Cid: c})
+		}
 	default:
 	}
 

pkg/policy/literal/literal_test.go

@@ -3,9 +3,13 @@ package literal
 import (
 	"testing"
 
+	"github.com/ipfs/go-cid"
 	"github.com/ipld/go-ipld-prime/datamodel"
+	cidlink "github.com/ipld/go-ipld-prime/linking/cid"
 	"github.com/ipld/go-ipld-prime/printer"
 	"github.com/stretchr/testify/require"
+
+	"github.com/ucan-wg/go-ucan/pkg/policy/limits"
 )
 
 func TestList(t *testing.T) {
@@ -53,6 +57,7 @@ func TestMap(t *testing.T) {
 				"barbar": "foo",
 			},
 		},
+		"link": cid.MustParse("bafzbeigai3eoy2ccc7ybwjfz5r3rdxqrinwi4rwytly24tdbh6yk7zslrm"),
 	})
 	require.NoError(t, err)
 
@@ -115,6 +120,190 @@ func TestMap(t *testing.T) {
 		string{"barbar"}: string{"foo"}
 	}
 }`, printer.Sprint(v))
+
+	v, err = n.LookupByString("link")
+	require.NoError(t, err)
+	require.Equal(t, datamodel.Kind_Link, v.Kind())
+	asLink, err := v.AsLink()
+	require.NoError(t, err)
+	require.True(t, asLink.(cidlink.Link).Equals(cid.MustParse("bafzbeigai3eoy2ccc7ybwjfz5r3rdxqrinwi4rwytly24tdbh6yk7zslrm")))
+}
+
+func TestAny(t *testing.T) {
+	data := map[string]any{
+		"bool":   true,
+		"string": "foobar",
+		"bytes":  []byte{1, 2, 3, 4},
+		"int":    1234,
+		"uint":   uint(12345),
+		"float":  1.45,
+		"slice":  []int{1, 2, 3},
+		"array":  [2]int{1, 2},
+		"map": map[string]any{
+			"foo": "bar",
+			"foofoo": map[string]string{
+				"barbar": "foo",
+			},
+		},
+		"link": cid.MustParse("bafzbeigai3eoy2ccc7ybwjfz5r3rdxqrinwi4rwytly24tdbh6yk7zslrm"),
+		"func": func() {},
+	}
+
+	v, err := Any(data["bool"])
+	require.NoError(t, err)
+	require.Equal(t, datamodel.Kind_Bool, v.Kind())
+	require.Equal(t, true, must(v.AsBool()))
+
+	v, err = Any(data["string"])
+	require.NoError(t, err)
+	require.Equal(t, datamodel.Kind_String, v.Kind())
+	require.Equal(t, "foobar", must(v.AsString()))
+
+	v, err = Any(data["bytes"])
+	require.NoError(t, err)
+	require.Equal(t, datamodel.Kind_Bytes, v.Kind())
+	require.Equal(t, []byte{1, 2, 3, 4}, must(v.AsBytes()))
+
+	v, err = Any(data["int"])
+	require.NoError(t, err)
+	require.Equal(t, datamodel.Kind_Int, v.Kind())
+	require.Equal(t, int64(1234), must(v.AsInt()))
+
+	v, err = Any(data["uint"])
+	require.NoError(t, err)
+	require.Equal(t, datamodel.Kind_Int, v.Kind())
+	require.Equal(t, int64(12345), must(v.AsInt()))
+
+	v, err = Any(data["float"])
+	require.NoError(t, err)
+	require.Equal(t, datamodel.Kind_Float, v.Kind())
+	require.Equal(t, 1.45, must(v.AsFloat()))
+
+	v, err = Any(data["slice"])
+	require.NoError(t, err)
+	require.Equal(t, datamodel.Kind_List, v.Kind())
+	require.Equal(t, int64(3), v.Length())
+	require.Equal(t, `list{
+	0: int{1}
+	1: int{2}
+	2: int{3}
+}`, printer.Sprint(v))
+
+	v, err = Any(data["array"])
+	require.NoError(t, err)
+	require.Equal(t, datamodel.Kind_List, v.Kind())
+	require.Equal(t, int64(2), v.Length())
+	require.Equal(t, `list{
+	0: int{1}
+	1: int{2}
+}`, printer.Sprint(v))
+
+	v, err = Any(data["map"])
+	require.NoError(t, err)
+	require.Equal(t, datamodel.Kind_Map, v.Kind())
+	require.Equal(t, int64(2), v.Length())
+	require.Equal(t, `map{
+	string{"foo"}: string{"bar"}
+	string{"foofoo"}: map{
+		string{"barbar"}: string{"foo"}
+	}
+}`, printer.Sprint(v))
+
+	v, err = Any(data["link"])
+	require.NoError(t, err)
+	require.Equal(t, datamodel.Kind_Link, v.Kind())
+	asLink, err := v.AsLink()
+	require.NoError(t, err)
+	require.True(t, asLink.(cidlink.Link).Equals(cid.MustParse("bafzbeigai3eoy2ccc7ybwjfz5r3rdxqrinwi4rwytly24tdbh6yk7zslrm")))
+
+	_, err = Any(data["func"])
+	require.Error(t, err)
+}
+
+func BenchmarkAny(b *testing.B) {
+	b.Run("bool", func(b *testing.B) {
+		b.ReportAllocs()
+
+		for n := 0; n < b.N; n++ {
+			_, _ = Any(true)
+		}
+	})
+
+	b.Run("string", func(b *testing.B) {
+		b.ReportAllocs()
+		for n := 0; n < b.N; n++ {
+			_, _ = Any("foobar")
+		}
+	})
+
+	b.Run("bytes", func(b *testing.B) {
+		b.ReportAllocs()
+		for n := 0; n < b.N; n++ {
+			_, _ = Any([]byte{1, 2, 3, 4})
+		}
+	})
+
+	b.Run("map", func(b *testing.B) {
+		b.ReportAllocs()
+		for n := 0; n < b.N; n++ {
+			_, _ = Any(map[string]any{
+				"foo": "bar",
+				"foofoo": map[string]string{
+					"barbar": "foo",
+				},
+			})
+		}
+	})
+}
+
+func TestAnyAssembleIntegerOverflow(t *testing.T) {
+	tests := []struct {
+		name      string
+		input     interface{}
+		shouldErr bool
+	}{
+		{
+			name:      "valid int",
+			input:     42,
+			shouldErr: false,
+		},
+		{
+			name:      "max safe int",
+			input:     limits.MaxInt53,
+			shouldErr: false,
+		},
+		{
+			name:      "min safe int",
+			input:     limits.MinInt53,
+			shouldErr: false,
+		},
+		{
+			name:      "overflow int",
+			input:     int64(limits.MaxInt53 + 1),
+			shouldErr: true,
+		},
+		{
+			name:      "underflow int",
+			input:     int64(limits.MinInt53 - 1),
+			shouldErr: true,
+		},
+		{
+			name:      "overflow uint",
+			input:     uint64(limits.MaxInt53 + 1),
+			shouldErr: true,
+		},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			_, err := Any(tt.input)
+			if tt.shouldErr {
+				require.Error(t, err)
+			} else {
+				require.NoError(t, err)
+			}
+		})
+	}
 }
 
 func must[T any](t T, err error) T {

pkg/policy/match.go

@@ -3,6 +3,7 @@ package policy
 import (
 	"cmp"
 	"fmt"
+	"math"
 
 	"github.com/ipld/go-ipld-prime"
 	"github.com/ipld/go-ipld-prime/datamodel"
@@ -10,17 +11,18 @@ import (
 )
 
 // Match determines if the IPLD node satisfies the policy.
-func (p Policy) Match(node datamodel.Node) bool {
+// The first Statement failing to match is returned as well.
+func (p Policy) Match(node datamodel.Node) (bool, Statement) {
 	for _, stmt := range p {
-		res, _ := matchStatement(stmt, node)
+		res, leaf := matchStatement(stmt, node)
 		switch res {
 		case matchResultNoData, matchResultFalse:
-			return false
+			return false, leaf
 		case matchResultOptionalNoData, matchResultTrue:
 			// continue
 		}
 	}
-	return true
+	return true, nil
 }
 
 // PartialMatch returns false IIF one non-optional Statement has the corresponding data and doesn't match.
@@ -80,6 +82,17 @@ func matchStatement(cur Statement, node ipld.Node) (_ matchResult, leafMost Stat
 			}
 			return boolToRes(datamodel.DeepEqual(s.value, res))
 		}
+	case KindNotEqual:
+		if s, ok := cur.(equality); ok {
+			res, err := s.selector.Select(node)
+			if err != nil {
+				return matchResultNoData, cur
+			}
+			if res == nil { // optional selector didn't match
+				return matchResultOptionalNoData, nil
+			}
+			return boolToRes(!datamodel.DeepEqual(s.value, res))
+		}
 	case KindGreaterThan:
 		if s, ok := cur.(equality); ok {
 			res, err := s.selector.Select(node)
@@ -131,9 +144,9 @@ func matchStatement(cur Statement, node ipld.Node) (_ matchResult, leafMost Stat
 			case matchResultNoData, matchResultOptionalNoData:
 				return res, leaf
 			case matchResultTrue:
-				return matchResultFalse, leaf
+				return matchResultFalse, cur
 			case matchResultFalse:
-				return matchResultTrue, leaf
+				return matchResultTrue, nil
 			}
 		}
 	case KindAnd:
@@ -248,10 +261,22 @@ func matchStatement(cur Statement, node ipld.Node) (_ matchResult, leafMost Stat
 	panic(fmt.Errorf("unimplemented statement kind: %s", cur.Kind()))
 }
 
+// isOrdered compares two IPLD nodes and returns true if they satisfy the given ordering function.
+// It supports comparison of integers and floats, returning false for:
+//   - Nodes of different or unsupported kinds
+//   - Integer values outside JavaScript's safe integer bounds (±2^53-1)
+//   - Non-finite floating point values (NaN or ±Inf)
+//
+// The satisfies parameter is a function that interprets the comparison result:
+//   - For ">" it returns true when order is 1
+//   - For ">=" it returns true when order is 0 or 1
+//   - For "<" it returns true when order is -1
+//   - For "<=" it returns true when order is -1 or 0
 func isOrdered(expected ipld.Node, actual ipld.Node, satisfies func(order int) bool) bool {
 	if expected.Kind() == ipld.Kind_Int && actual.Kind() == ipld.Kind_Int {
 		a := must.Int(actual)
 		b := must.Int(expected)
+
 		return satisfies(cmp.Compare(a, b))
 	}
 
@@ -264,6 +289,11 @@ func isOrdered(expected ipld.Node, actual ipld.Node, satisfies func(order int) b
 		if err != nil {
 			panic(fmt.Errorf("extracting selector float: %w", err))
 		}
+
+		if math.IsInf(a, 0) || math.IsNaN(a) || math.IsInf(b, 0) || math.IsNaN(b) {
+			return false
+		}
+
 		return satisfies(cmp.Compare(a, b))
 	}
 

pkg/policy/match_test.go

@@ -16,229 +16,420 @@ import (
 
 func TestMatch(t *testing.T) {
 	t.Run("equality", func(t *testing.T) {
-		t.Run("string", func(t *testing.T) {
-			np := basicnode.Prototype.String
-			nb := np.NewBuilder()
-			nb.AssignString("test")
-			nd := nb.Build()
+		t.Run("eq string", func(t *testing.T) {
+			nd := literal.String("test")
 
 			pol := MustConstruct(Equal(".", literal.String("test")))
-			ok := pol.Match(nd)
+			ok, leaf := pol.Match(nd)
 			require.True(t, ok)
+			require.Nil(t, leaf)
 
 			pol = MustConstruct(Equal(".", literal.String("test2")))
-			ok = pol.Match(nd)
+			ok, leaf = pol.Match(nd)
 			require.False(t, ok)
+			require.Equal(t, pol[0], leaf)
 
 			pol = MustConstruct(Equal(".", literal.Int(138)))
-			ok = pol.Match(nd)
+			ok, leaf = pol.Match(nd)
 			require.False(t, ok)
+			require.Equal(t, pol[0], leaf)
 		})
 
-		t.Run("int", func(t *testing.T) {
-			np := basicnode.Prototype.Int
-			nb := np.NewBuilder()
-			nb.AssignInt(138)
-			nd := nb.Build()
+		t.Run("eq int", func(t *testing.T) {
+			nd := literal.Int(138)
 
 			pol := MustConstruct(Equal(".", literal.Int(138)))
-			ok := pol.Match(nd)
+			ok, leaf := pol.Match(nd)
 			require.True(t, ok)
+			require.Nil(t, leaf)
 
 			pol = MustConstruct(Equal(".", literal.Int(1138)))
-			ok = pol.Match(nd)
+			ok, leaf = pol.Match(nd)
 			require.False(t, ok)
+			require.Equal(t, pol[0], leaf)
 
 			pol = MustConstruct(Equal(".", literal.String("138")))
-			ok = pol.Match(nd)
+			ok, leaf = pol.Match(nd)
 			require.False(t, ok)
+			require.Equal(t, pol[0], leaf)
 		})
 
-		t.Run("float", func(t *testing.T) {
-			np := basicnode.Prototype.Float
-			nb := np.NewBuilder()
-			nb.AssignFloat(1.138)
-			nd := nb.Build()
+		t.Run("eq float", func(t *testing.T) {
+			nd := literal.Float(1.138)
 
 			pol := MustConstruct(Equal(".", literal.Float(1.138)))
-			ok := pol.Match(nd)
+			ok, leaf := pol.Match(nd)
 			require.True(t, ok)
+			require.Nil(t, leaf)
 
 			pol = MustConstruct(Equal(".", literal.Float(11.38)))
-			ok = pol.Match(nd)
+			ok, leaf = pol.Match(nd)
 			require.False(t, ok)
+			require.Equal(t, pol[0], leaf)
 
 			pol = MustConstruct(Equal(".", literal.String("138")))
-			ok = pol.Match(nd)
+			ok, leaf = pol.Match(nd)
 			require.False(t, ok)
+			require.Equal(t, pol[0], leaf)
 		})
 
-		t.Run("IPLD Link", func(t *testing.T) {
+		t.Run("eq IPLD Link", func(t *testing.T) {
 			l0 := cidlink.Link{Cid: cid.MustParse("bafybeif4owy5gno5lwnixqm52rwqfodklf76hsetxdhffuxnplvijskzqq")}
 			l1 := cidlink.Link{Cid: cid.MustParse("bafkreifau35r7vi37tvbvfy3hdwvgb4tlflqf7zcdzeujqcjk3rsphiwte")}
 
-			np := basicnode.Prototype.Link
-			nb := np.NewBuilder()
-			nb.AssignLink(l0)
-			nd := nb.Build()
+			nd := literal.Link(l0)
 
 			pol := MustConstruct(Equal(".", literal.Link(l0)))
-			ok := pol.Match(nd)
+			ok, leaf := pol.Match(nd)
 			require.True(t, ok)
+			require.Nil(t, leaf)
 
 			pol = MustConstruct(Equal(".", literal.Link(l1)))
-			ok = pol.Match(nd)
+			ok, leaf = pol.Match(nd)
 			require.False(t, ok)
+			require.Equal(t, pol[0], leaf)
 
 			pol = MustConstruct(Equal(".", literal.String("bafybeif4owy5gno5lwnixqm52rwqfodklf76hsetxdhffuxnplvijskzqq")))
-			ok = pol.Match(nd)
+			ok, leaf = pol.Match(nd)
 			require.False(t, ok)
+			require.Equal(t, pol[0], leaf)
 		})
 
-		t.Run("string in map", func(t *testing.T) {
-			np := basicnode.Prototype.Map
-			nb := np.NewBuilder()
-			ma, _ := nb.BeginMap(1)
-			ma.AssembleKey().AssignString("foo")
-			ma.AssembleValue().AssignString("bar")
-			ma.Finish()
-			nd := nb.Build()
+		t.Run("eq string in map", func(t *testing.T) {
+			nd, _ := literal.Map(map[string]any{
+				"foo": "bar",
+			})
 
 			pol := MustConstruct(Equal(".foo", literal.String("bar")))
-			ok := pol.Match(nd)
+			ok, leaf := pol.Match(nd)
 			require.True(t, ok)
+			require.Nil(t, leaf)
 
 			pol = MustConstruct(Equal(".[\"foo\"]", literal.String("bar")))
-			ok = pol.Match(nd)
+			ok, leaf = pol.Match(nd)
 			require.True(t, ok)
+			require.Nil(t, leaf)
 
 			pol = MustConstruct(Equal(".foo", literal.String("baz")))
-			ok = pol.Match(nd)
+			ok, leaf = pol.Match(nd)
 			require.False(t, ok)
+			require.Equal(t, pol[0], leaf)
 
 			pol = MustConstruct(Equal(".foobar", literal.String("bar")))
-			ok = pol.Match(nd)
+			ok, leaf = pol.Match(nd)
 			require.False(t, ok)
+			require.Equal(t, pol[0], leaf)
 		})
 
-		t.Run("string in list", func(t *testing.T) {
-			np := basicnode.Prototype.List
-			nb := np.NewBuilder()
-			la, _ := nb.BeginList(1)
-			la.AssembleValue().AssignString("foo")
-			la.Finish()
-			nd := nb.Build()
+		t.Run("eq string in list", func(t *testing.T) {
+			nd, _ := literal.List([]any{"foo"})
 
 			pol := MustConstruct(Equal(".[0]", literal.String("foo")))
-			ok := pol.Match(nd)
+			ok, leaf := pol.Match(nd)
 			require.True(t, ok)
+			require.Nil(t, leaf)
 
 			pol = MustConstruct(Equal(".[1]", literal.String("foo")))
-			ok = pol.Match(nd)
+			ok, leaf = pol.Match(nd)
 			require.False(t, ok)
+			require.Equal(t, pol[0], leaf)
+		})
+
+		t.Run("neq string", func(t *testing.T) {
+			nd := literal.String("test")
+
+			pol := MustConstruct(NotEqual(".", literal.String("test")))
+			ok, leaf := pol.Match(nd)
+			require.False(t, ok)
+			require.Equal(t, pol[0], leaf)
+
+			pol = MustConstruct(NotEqual(".", literal.String("test2")))
+			ok, leaf = pol.Match(nd)
+			require.True(t, ok)
+			require.Nil(t, leaf)
+
+			pol = MustConstruct(NotEqual(".", literal.Int(138)))
+			ok, leaf = pol.Match(nd)
+			require.True(t, ok)
+			require.Nil(t, leaf)
+		})
+
+		t.Run("neq int", func(t *testing.T) {
+			nd := literal.Int(138)
+
+			pol := MustConstruct(NotEqual(".", literal.Int(138)))
+			ok, leaf := pol.Match(nd)
+			require.False(t, ok)
+			require.Equal(t, pol[0], leaf)
+
+			pol = MustConstruct(NotEqual(".", literal.Int(1138)))
+			ok, leaf = pol.Match(nd)
+			require.True(t, ok)
+			require.Nil(t, leaf)
+
+			pol = MustConstruct(NotEqual(".", literal.String("138")))
+			ok, leaf = pol.Match(nd)
+			require.True(t, ok)
+			require.Nil(t, leaf)
+		})
+
+		t.Run("neq float", func(t *testing.T) {
+			nd := literal.Float(1.138)
+
+			pol := MustConstruct(NotEqual(".", literal.Float(1.138)))
+			ok, leaf := pol.Match(nd)
+			require.False(t, ok)
+			require.Equal(t, pol[0], leaf)
+
+			pol = MustConstruct(NotEqual(".", literal.Float(11.38)))
+			ok, leaf = pol.Match(nd)
+			require.True(t, ok)
+			require.Nil(t, leaf)
+
+			pol = MustConstruct(NotEqual(".", literal.String("138")))
+			ok, leaf = pol.Match(nd)
+			require.True(t, ok)
+			require.Nil(t, leaf)
+		})
+
+		t.Run("neq IPLD Link", func(t *testing.T) {
+			l0 := cidlink.Link{Cid: cid.MustParse("bafybeif4owy5gno5lwnixqm52rwqfodklf76hsetxdhffuxnplvijskzqq")}
+			l1 := cidlink.Link{Cid: cid.MustParse("bafkreifau35r7vi37tvbvfy3hdwvgb4tlflqf7zcdzeujqcjk3rsphiwte")}
+
+			nd := literal.Link(l0)
+
+			pol := MustConstruct(NotEqual(".", literal.Link(l0)))
+			ok, leaf := pol.Match(nd)
+			require.False(t, ok)
+			require.Equal(t, pol[0], leaf)
+
+			pol = MustConstruct(NotEqual(".", literal.Link(l1)))
+			ok, leaf = pol.Match(nd)
+			require.True(t, ok)
+			require.Nil(t, leaf)
+
+			pol = MustConstruct(NotEqual(".", literal.String("bafybeif4owy5gno5lwnixqm52rwqfodklf76hsetxdhffuxnplvijskzqq")))
+			ok, leaf = pol.Match(nd)
+			require.True(t, ok)
+			require.Nil(t, leaf)
+		})
+
+		t.Run("neq string in map", func(t *testing.T) {
+			nd, _ := literal.Map(map[string]any{
+				"foo": "bar",
+			})
+
+			pol := MustConstruct(NotEqual(".foo", literal.String("bar")))
+			ok, leaf := pol.Match(nd)
+			require.False(t, ok)
+			require.Equal(t, pol[0], leaf)
+
+			pol = MustConstruct(NotEqual(".[\"foo\"]", literal.String("bar")))
+			ok, leaf = pol.Match(nd)
+			require.False(t, ok)
+			require.Equal(t, pol[0], leaf)
+
+			pol = MustConstruct(NotEqual(".foo", literal.String("baz")))
+			ok, leaf = pol.Match(nd)
+			require.True(t, ok)
+			require.Nil(t, leaf)
+
+			// missing data will fail, as not optional
+			pol = MustConstruct(NotEqual(".foobar", literal.String("bar")))
+			ok, leaf = pol.Match(nd)
+			require.False(t, ok)
+			require.Equal(t, pol[0], leaf)
+		})
+
+		t.Run("neq string in list", func(t *testing.T) {
+			nd, _ := literal.List([]any{"foo"})
+
+			pol := MustConstruct(NotEqual(".[0]", literal.String("foo")))
+			ok, leaf := pol.Match(nd)
+			require.False(t, ok)
+			require.Equal(t, pol[0], leaf)
+
+			pol = MustConstruct(NotEqual(".[0]", literal.String("bar")))
+			ok, leaf = pol.Match(nd)
+			require.True(t, ok)
+			require.Nil(t, leaf)
+
+			// missing data will fail, as not optional
+			pol = MustConstruct(NotEqual(".[1]", literal.String("foo")))
+			ok, leaf = pol.Match(nd)
+			require.False(t, ok)
+			require.Equal(t, pol[0], leaf)
 		})
 	})
 
 	t.Run("inequality", func(t *testing.T) {
 		t.Run("gt int", func(t *testing.T) {
-			np := basicnode.Prototype.Int
-			nb := np.NewBuilder()
-			nb.AssignInt(138)
-			nd := nb.Build()
+			nd := literal.Int(138)
 
 			pol := MustConstruct(GreaterThan(".", literal.Int(1)))
-			ok := pol.Match(nd)
+			ok, leaf := pol.Match(nd)
 			require.True(t, ok)
+			require.Nil(t, leaf)
+
+			pol = MustConstruct(GreaterThan(".", literal.Int(138)))
+			ok, leaf = pol.Match(nd)
+			require.False(t, ok)
+			require.Equal(t, pol[0], leaf)
+
+			pol = MustConstruct(GreaterThan(".", literal.Int(140)))
+			ok, leaf = pol.Match(nd)
+			require.False(t, ok)
+			require.Equal(t, pol[0], leaf)
 		})
 
 		t.Run("gte int", func(t *testing.T) {
-			np := basicnode.Prototype.Int
-			nb := np.NewBuilder()
-			nb.AssignInt(138)
-			nd := nb.Build()
+			nd := literal.Int(138)
 
 			pol := MustConstruct(GreaterThanOrEqual(".", literal.Int(1)))
-			ok := pol.Match(nd)
+			ok, leaf := pol.Match(nd)
 			require.True(t, ok)
+			require.Nil(t, leaf)
 
 			pol = MustConstruct(GreaterThanOrEqual(".", literal.Int(138)))
-			ok = pol.Match(nd)
+			ok, leaf = pol.Match(nd)
 			require.True(t, ok)
+			require.Nil(t, leaf)
+
+			pol = MustConstruct(GreaterThanOrEqual(".", literal.Int(140)))
+			ok, leaf = pol.Match(nd)
+			require.False(t, ok)
+			require.Equal(t, pol[0], leaf)
 		})
 
 		t.Run("gt float", func(t *testing.T) {
-			np := basicnode.Prototype.Float
-			nb := np.NewBuilder()
-			nb.AssignFloat(1.38)
-			nd := nb.Build()
+			nd := literal.Float(1.38)
 
 			pol := MustConstruct(GreaterThan(".", literal.Float(1)))
-			ok := pol.Match(nd)
+			ok, leaf := pol.Match(nd)
 			require.True(t, ok)
+			require.Nil(t, leaf)
+
+			pol = MustConstruct(GreaterThan(".", literal.Float(2)))
+			ok, leaf = pol.Match(nd)
+			require.False(t, ok)
+			require.Equal(t, pol[0], leaf)
 		})
 
 		t.Run("gte float", func(t *testing.T) {
-			np := basicnode.Prototype.Float
-			nb := np.NewBuilder()
-			nb.AssignFloat(1.38)
-			nd := nb.Build()
+			nd := literal.Float(1.38)
 
 			pol := MustConstruct(GreaterThanOrEqual(".", literal.Float(1)))
-			ok := pol.Match(nd)
+			ok, leaf := pol.Match(nd)
 			require.True(t, ok)
+			require.Nil(t, leaf)
 
 			pol = MustConstruct(GreaterThanOrEqual(".", literal.Float(1.38)))
-			ok = pol.Match(nd)
+			ok, leaf = pol.Match(nd)
 			require.True(t, ok)
+			require.Nil(t, leaf)
+
+			pol = MustConstruct(GreaterThanOrEqual(".", literal.Float(2)))
+			ok, leaf = pol.Match(nd)
+			require.False(t, ok)
+			require.Equal(t, pol[0], leaf)
 		})
 
 		t.Run("lt int", func(t *testing.T) {
-			np := basicnode.Prototype.Int
-			nb := np.NewBuilder()
-			nb.AssignInt(138)
-			nd := nb.Build()
+			nd := literal.Int(138)
 
 			pol := MustConstruct(LessThan(".", literal.Int(1138)))
-			ok := pol.Match(nd)
+			ok, leaf := pol.Match(nd)
 			require.True(t, ok)
+			require.Nil(t, leaf)
+
+			pol = MustConstruct(LessThan(".", literal.Int(138)))
+			ok, leaf = pol.Match(nd)
+			require.False(t, ok)
+			require.Equal(t, pol[0], leaf)
+
+			pol = MustConstruct(LessThan(".", literal.Int(100)))
+			ok, leaf = pol.Match(nd)
+			require.False(t, ok)
+			require.Equal(t, pol[0], leaf)
 		})
 
 		t.Run("lte int", func(t *testing.T) {
-			np := basicnode.Prototype.Int
-			nb := np.NewBuilder()
-			nb.AssignInt(138)
-			nd := nb.Build()
+			nd := literal.Int(138)
 
 			pol := MustConstruct(LessThanOrEqual(".", literal.Int(1138)))
-			ok := pol.Match(nd)
+			ok, leaf := pol.Match(nd)
 			require.True(t, ok)
+			require.Nil(t, leaf)
 
 			pol = MustConstruct(LessThanOrEqual(".", literal.Int(138)))
-			ok = pol.Match(nd)
+			ok, leaf = pol.Match(nd)
 			require.True(t, ok)
+			require.Nil(t, leaf)
+
+			pol = MustConstruct(LessThanOrEqual(".", literal.Int(100)))
+			ok, leaf = pol.Match(nd)
+			require.False(t, ok)
+			require.Equal(t, pol[0], leaf)
+		})
+
+		t.Run("lt float", func(t *testing.T) {
+			nd := literal.Float(1.38)
+
+			pol := MustConstruct(LessThan(".", literal.Float(1)))
+			ok, leaf := pol.Match(nd)
+			require.False(t, ok)
+			require.Equal(t, pol[0], leaf)
+
+			pol = MustConstruct(LessThan(".", literal.Float(2)))
+			ok, leaf = pol.Match(nd)
+			require.True(t, ok)
+			require.Nil(t, leaf)
+		})
+
+		t.Run("lte float", func(t *testing.T) {
+			nd := literal.Float(1.38)
+
+			pol := MustConstruct(LessThanOrEqual(".", literal.Float(1)))
+			ok, leaf := pol.Match(nd)
+			require.False(t, ok)
+			require.Equal(t, pol[0], leaf)
+
+			pol = MustConstruct(GreaterThanOrEqual(".", literal.Float(1.38)))
+			ok, leaf = pol.Match(nd)
+			require.True(t, ok)
+			require.Nil(t, leaf)
+
+			pol = MustConstruct(LessThanOrEqual(".", literal.Float(2)))
+			ok, leaf = pol.Match(nd)
+			require.True(t, ok)
+			require.Nil(t, leaf)
 		})
 	})
 
 	t.Run("negation", func(t *testing.T) {
-		np := basicnode.Prototype.Bool
-		nb := np.NewBuilder()
-		nb.AssignBool(false)
-		nd := nb.Build()
+		nd, _ := literal.Map(map[string]any{
+			"foo": false,
+		})
 
-		pol := MustConstruct(Not(Equal(".", literal.Bool(true))))
-		ok := pol.Match(nd)
+		pol := MustConstruct(Not(Equal(".foo", literal.Bool(true))))
+		ok, leaf := pol.Match(nd)
 		require.True(t, ok)
+		require.Nil(t, leaf)
 
-		pol = MustConstruct(Not(Equal(".", literal.Bool(false))))
-		ok = pol.Match(nd)
+		pol = MustConstruct(Not(Equal(".foo", literal.Bool(false))))
+		ok, leaf = pol.Match(nd)
 		require.False(t, ok)
+		require.Equal(t, pol[0], leaf)
+
+		// missing data will fail, as not optional
+		pol = MustConstruct(Not(Equal(".foobar", literal.Bool(true))))
+		ok, leaf = pol.Match(nd)
+		require.False(t, ok)
+		require.Equal(t, MustConstruct(Equal(".foobar", literal.Bool(true)))[0], leaf)
 	})
 
 	t.Run("conjunction", func(t *testing.T) {
-		np := basicnode.Prototype.Int
-		nb := np.NewBuilder()
-		nb.AssignInt(138)
-		nd := nb.Build()
+		nd := literal.Int(138)
 
 		pol := MustConstruct(
 			And(
@@ -246,8 +437,9 @@ func TestMatch(t *testing.T) {
 				LessThan(".", literal.Int(1138)),
 			),
 		)
-		ok := pol.Match(nd)
+		ok, leaf := pol.Match(nd)
 		require.True(t, ok)
+		require.Nil(t, leaf)
 
 		pol = MustConstruct(
 			And(
@@ -255,19 +447,18 @@ func TestMatch(t *testing.T) {
 				Equal(".", literal.Int(1138)),
 			),
 		)
-		ok = pol.Match(nd)
+		ok, leaf = pol.Match(nd)
 		require.False(t, ok)
+		require.Equal(t, MustConstruct(Equal(".", literal.Int(1138)))[0], leaf)
 
 		pol = MustConstruct(And())
-		ok = pol.Match(nd)
+		ok, leaf = pol.Match(nd)
 		require.True(t, ok)
+		require.Nil(t, leaf)
 	})
 
 	t.Run("disjunction", func(t *testing.T) {
-		np := basicnode.Prototype.Int
-		nb := np.NewBuilder()
-		nb.AssignInt(138)
-		nd := nb.Build()
+		nd := literal.Int(138)
 
 		pol := MustConstruct(
 			Or(
@@ -275,8 +466,9 @@ func TestMatch(t *testing.T) {
 				LessThan(".", literal.Int(1138)),
 			),
 		)
-		ok := pol.Match(nd)
+		ok, leaf := pol.Match(nd)
 		require.True(t, ok)
+		require.Nil(t, leaf)
 
 		pol = MustConstruct(
 			Or(
@@ -284,12 +476,14 @@ func TestMatch(t *testing.T) {
 				Equal(".", literal.Int(1138)),
 			),
 		)
-		ok = pol.Match(nd)
+		ok, leaf = pol.Match(nd)
 		require.False(t, ok)
+		require.Equal(t, pol[0], leaf)
 
 		pol = MustConstruct(Or())
-		ok = pol.Match(nd)
+		ok, leaf = pol.Match(nd)
 		require.True(t, ok)
+		require.Nil(t, leaf)
 	})
 
 	t.Run("wildcard", func(t *testing.T) {
@@ -303,14 +497,12 @@ func TestMatch(t *testing.T) {
 		} {
 			func(s string) {
 				t.Run(fmt.Sprintf("pass %s", s), func(t *testing.T) {
-					np := basicnode.Prototype.String
-					nb := np.NewBuilder()
-					nb.AssignString(s)
-					nd := nb.Build()
+					nd := literal.String(s)
 
 					pol := MustConstruct(Like(".", pattern))
-					ok := pol.Match(nd)
+					ok, leaf := pol.Match(nd)
 					require.True(t, ok)
+					require.Nil(t, leaf)
 				})
 			}(s)
 		}
@@ -324,70 +516,56 @@ func TestMatch(t *testing.T) {
 		} {
 			func(s string) {
 				t.Run(fmt.Sprintf("fail %s", s), func(t *testing.T) {
-					np := basicnode.Prototype.String
-					nb := np.NewBuilder()
-					nb.AssignString(s)
-					nd := nb.Build()
+					nd := literal.String(s)
 
 					pol := MustConstruct(Like(".", pattern))
-					ok := pol.Match(nd)
+					ok, leaf := pol.Match(nd)
 					require.False(t, ok)
+					require.Equal(t, pol[0], leaf)
 				})
 			}(s)
 		}
 	})
 
 	t.Run("quantification", func(t *testing.T) {
-		buildValueNode := func(v int64) ipld.Node {
-			np := basicnode.Prototype.Map
-			nb := np.NewBuilder()
-			ma, _ := nb.BeginMap(1)
-			ma.AssembleKey().AssignString("value")
-			ma.AssembleValue().AssignInt(v)
-			ma.Finish()
-			return nb.Build()
-		}
-
 		t.Run("all", func(t *testing.T) {
-			np := basicnode.Prototype.List
-			nb := np.NewBuilder()
-			la, _ := nb.BeginList(5)
-			la.AssembleValue().AssignNode(buildValueNode(5))
-			la.AssembleValue().AssignNode(buildValueNode(10))
-			la.AssembleValue().AssignNode(buildValueNode(20))
-			la.AssembleValue().AssignNode(buildValueNode(50))
-			la.AssembleValue().AssignNode(buildValueNode(100))
-			la.Finish()
-			nd := nb.Build()
+			nd, _ := literal.List([]any{
+				map[string]int{"value": 5},
+				map[string]int{"value": 10},
+				map[string]int{"value": 20},
+				map[string]int{"value": 50},
+				map[string]int{"value": 100},
+			})
 
 			pol := MustConstruct(All(".[]", GreaterThan(".value", literal.Int(2))))
-			ok := pol.Match(nd)
+			ok, leaf := pol.Match(nd)
 			require.True(t, ok)
+			require.Nil(t, leaf)
 
 			pol = MustConstruct(All(".[]", GreaterThan(".value", literal.Int(20))))
-			ok = pol.Match(nd)
+			ok, leaf = pol.Match(nd)
 			require.False(t, ok)
+			require.Equal(t, MustConstruct(GreaterThan(".value", literal.Int(20)))[0], leaf)
 		})
 
 		t.Run("any", func(t *testing.T) {
-			np := basicnode.Prototype.List
-			nb := np.NewBuilder()
-			la, _ := nb.BeginList(5)
-			la.AssembleValue().AssignNode(buildValueNode(5))
-			la.AssembleValue().AssignNode(buildValueNode(10))
-			la.AssembleValue().AssignNode(buildValueNode(20))
-			la.AssembleValue().AssignNode(buildValueNode(50))
-			la.AssembleValue().AssignNode(buildValueNode(100))
-			la.Finish()
-			nd := nb.Build()
+			nd, _ := literal.List([]any{
+				map[string]int{"value": 5},
+				map[string]int{"value": 10},
+				map[string]int{"value": 20},
+				map[string]int{"value": 50},
+				map[string]int{"value": 100},
+			})
 
 			pol := MustConstruct(Any(".[]", GreaterThan(".value", literal.Int(60))))
-			ok := pol.Match(nd)
+			ok, leaf := pol.Match(nd)
 			require.True(t, ok)
+			require.Nil(t, leaf)
 
 			pol = MustConstruct(Any(".[]", GreaterThan(".value", literal.Int(100))))
-			ok = pol.Match(nd)
+			ok, leaf = pol.Match(nd)
 			require.False(t, ok)
+			require.Equal(t, pol[0], leaf)
 		})
 	})
 }
@@ -405,7 +583,8 @@ func TestPolicyExamples(t *testing.T) {
 
 		pol, err := FromDagJson(policy)
 		require.NoError(t, err)
-		return pol.Match(data)
+		res, _ := pol.Match(data)
+		return res
 	}
 
 	t.Run("And", func(t *testing.T) {
@@ -470,6 +649,7 @@ func FuzzMatch(f *testing.F) {
 	f.Add([]byte(`[["all", ".reviewer", ["like", ".email", "*@example.com"]]]`), []byte(`{"reviewer": [{"email": "alice@example.com"}, {"email": "bob@example.com"}]}`))
 	f.Add([]byte(`[["any", ".tags", ["or", [["==", ".", "news"], ["==", ".", "press"]]]]]`), []byte(`{"tags": ["news", "press"]}`))
 	f.Add([]byte(`[["==", ".name", "Alice"]]`), []byte(`{"name": "Alice"}`))
+	f.Add([]byte(`[["!=", ".name", "Alice"]]`), []byte(`{"name": "Alice"}`))
 	f.Add([]byte(`[[">", ".age", 30]]`), []byte(`{"age": 31}`))
 	f.Add([]byte(`[["<=", ".height", 180]]`), []byte(`{"height": 170}`))
 	f.Add([]byte(`[["not", ["==", ".status", "inactive"]]]`), []byte(`{"status": "active"}`))
@@ -509,7 +689,7 @@ func FuzzMatch(f *testing.F) {
 			t.Skip()
 		}
 
-		policy.Match(dataNode)
+		_, _ = policy.Match(dataNode)
 	})
 }
 
@@ -584,7 +764,7 @@ func TestOptionalSelectors(t *testing.T) {
 			err = nb.AssignNode(n)
 			require.NoError(t, err)
 
-			result := tt.policy.Match(nb.Build())
+			result, _ := tt.policy.Match(nb.Build())
 			require.Equal(t, tt.expected, result)
 		})
 	}

pkg/policy/policy.go

@@ -14,6 +14,7 @@ import (
 
 const (
 	KindEqual              = "=="   // implemented by equality
+	KindNotEqual           = "!="   // implemented by equality
 	KindGreaterThan        = ">"    // implemented by equality
 	KindGreaterThanOrEqual = ">="   // implemented by equality
 	KindLessThan           = "<"    // implemented by equality
@@ -87,6 +88,13 @@ func Equal(selector string, value ipld.Node) Constructor {
 	}
 }
 
+func NotEqual(selector string, value ipld.Node) Constructor {
+	return func() (Statement, error) {
+		sel, err := selpkg.Parse(selector)
+		return equality{kind: KindNotEqual, selector: sel, value: value}, err
+	}
+}
+
 func GreaterThan(selector string, value ipld.Node) Constructor {
 	return func() (Statement, error) {
 		sel, err := selpkg.Parse(selector)
@@ -125,7 +133,7 @@ func (n negation) Kind() string {
 
 func (n negation) String() string {
 	child := n.statement.String()
-	return fmt.Sprintf(`["%s", "%s"]`, n.Kind(), strings.ReplaceAll(child, "\n", "\n  "))
+	return fmt.Sprintf(`["%s", %s]`, n.Kind(), strings.ReplaceAll(child, "\n", "\n  "))
 }
 
 func Not(cstor Constructor) Constructor {
@@ -149,7 +157,7 @@ func (c connective) String() string {
 	for i, statement := range c.statements {
 		childs[i] = strings.ReplaceAll(statement.String(), "\n", "\n  ")
 	}
-	return fmt.Sprintf("[\"%s\", [\n  %s]]\n", c.kind, strings.Join(childs, ",\n  "))
+	return fmt.Sprintf("[\"%s\", [\n  %s\n]]", c.kind, strings.Join(childs, ",\n  "))
 }
 
 func And(cstors ...Constructor) Constructor {
@@ -208,7 +216,7 @@ func (n quantifier) Kind() string {
 
 func (n quantifier) String() string {
 	child := n.statement.String()
-	return fmt.Sprintf("[\"%s\", \"%s\",\n  %s]", n.Kind(), n.selector, strings.ReplaceAll(child, "\n", "\n  "))
+	return fmt.Sprintf("[\"%s\", \"%s\",\n  %s\n]", n.Kind(), n.selector, strings.ReplaceAll(child, "\n", "\n  "))
 }
 
 func All(selector string, cstor Constructor) Constructor {

pkg/policy/policy_test.go

@@ -28,12 +28,47 @@ func ExamplePolicy() {
 	// [
 	//   ["==", ".status", "draft"],
 	//   ["all", ".reviewer",
-	//     ["like", ".email", "*@example.com"]],
+	//     ["like", ".email", "*@example.com"]
+	//   ],
 	//   ["any", ".tags",
 	//     ["or", [
 	//       ["==", ".", "news"],
-	//       ["==", ".", "press"]]]
-	//     ]
+	//       ["==", ".", "press"]
+	//     ]]
+	//   ]
+	// ]
+}
+
+func ExamplePolicy_accumulate() {
+	var statements []policy.Constructor
+
+	statements = append(statements, policy.Equal(".status", literal.String("draft")))
+
+	statements = append(statements, policy.All(".reviewer",
+		policy.Like(".email", "*@example.com"),
+	))
+
+	statements = append(statements, policy.Any(".tags", policy.Or(
+		policy.Equal(".", literal.String("news")),
+		policy.Equal(".", literal.String("press")),
+	)))
+
+	pol := policy.MustConstruct(statements...)
+
+	fmt.Println(pol)
+
+	// Output:
+	// [
+	//   ["==", ".status", "draft"],
+	//   ["all", ".reviewer",
+	//     ["like", ".email", "*@example.com"]
+	//   ],
+	//   ["any", ".tags",
+	//     ["or", [
+	//       ["==", ".", "news"],
+	//       ["==", ".", "press"]
+	//     ]]
+	//   ]
 	// ]
 }
 

pkg/policy/policytest/spec.go

@@ -0,0 +1,67 @@
+package policytest
+
+import (
+	"github.com/ipld/go-ipld-prime"
+
+	"github.com/ucan-wg/go-ucan/pkg/args"
+	"github.com/ucan-wg/go-ucan/pkg/policy"
+	"github.com/ucan-wg/go-ucan/pkg/policy/literal"
+)
+
+// EmptyPolicy provides a Policy with no statements.
+var EmptyPolicy = policy.Policy{}
+
+// SpecPolicy provides a  valid Policy containing the statements that are included
+// in the second code block of the [Validation] section of the delegation specification.
+//
+// [Validation]: https://github.com/ucan-wg/delegation/tree/v1_ipld#validation
+var SpecPolicy = policy.MustConstruct(
+	policy.Equal(".from", literal.String("alice@example.com")),
+	policy.Any(".to", policy.Like(".", "*@example.com")),
+)
+
+// TODO: Replace the URL for [Validation] above when the delegation
+//       specification has been finished/merged.
+
+// SpecValidArguments provides valid, instantiated Arguments containing
+// the key/value pairs that are included in portion of the second code block
+// of the [Validation] section of the delegation specification.
+//
+// [Validation]: https://github.com/ucan-wg/delegation/tree/v1_ipld#validation
+var SpecValidArguments = args.NewBuilder().
+	Add("from", "alice@example.com").
+	Add("to", []string{
+		"bob@example.com",
+		"carol@not.example.com",
+	}).
+	Add("title", "Coffee").
+	Add("body", "Still on for coffee").
+	MustBuild()
+
+var specValidArgumentsIPLD = mustIPLD(SpecValidArguments)
+
+// SpecInvalidArguments provides invalid, instantiated Arguments containing
+// the key/value pairs that are included in portion of the second code block
+// of the [Validation] section of the delegation specification.
+//
+// [Validation]: https://github.com/ucan-wg/delegation/tree/v1_ipld#validation
+var SpecInvalidArguments = args.NewBuilder().
+	Add("from", "alice@example.com").
+	Add("to", []string{
+		"bob@null.com",
+		"carol@elsewhere.example.com",
+	}).
+	Add("title", "Coffee").
+	Add("body", "Still on for coffee").
+	MustBuild()
+
+var specInvalidArgumentsIPLD = mustIPLD(SpecInvalidArguments)
+
+func mustIPLD(args *args.Args) ipld.Node {
+	node, err := args.ToIPLD()
+	if err != nil {
+		panic(err)
+	}
+
+	return node
+}

pkg/policy/policytest/spec_test.go

@@ -0,0 +1,32 @@
+package policytest
+
+import (
+	"testing"
+
+	"github.com/stretchr/testify/assert"
+)
+
+// TestInvocationValidation applies the example policy to the second
+// example arguments as defined in the [Validation] section of the
+// invocation specification.
+//
+// [Validation]: https://github.com/ucan-wg/delegation/tree/v1_ipld#validation
+func TestInvocationValidationSpecExamples(t *testing.T) {
+	t.Parallel()
+
+	t.Run("with passing args", func(t *testing.T) {
+		t.Parallel()
+
+		exec, stmt := SpecPolicy.Match(specValidArgumentsIPLD)
+		assert.True(t, exec)
+		assert.Nil(t, stmt)
+	})
+
+	t.Run("fails on recipients (second statement)", func(t *testing.T) {
+		t.Parallel()
+
+		exec, stmt := SpecPolicy.Match(specInvalidArgumentsIPLD)
+		assert.False(t, exec)
+		assert.NotNil(t, stmt)
+	})
+}

pkg/policy/selector/parsing.go

@@ -6,12 +6,24 @@ import (
 	"regexp"
 	"strconv"
 	"strings"
+
+	"github.com/ucan-wg/go-ucan/pkg/policy/limits"
 )
 
 var (
 	indexRegex = regexp.MustCompile(`^-?\d+$`)
 	sliceRegex = regexp.MustCompile(`^((\-?\d+:\-?\d*)|(\-?\d*:\-?\d+))$`)
-	fieldRegex = regexp.MustCompile(`^\.[a-zA-Z_]*?$`)
+
+	// Field name requirements:
+	// - Must start with ASCII letter, Unicode letter, or underscore
+	// - Can contain:
+	//   - ASCII letters (a-z, A-Z)
+	//   - ASCII digits (0-9)
+	//   - Unicode letters (\p{L})
+	//   - Dollar sign ($)
+	//   - Underscore (_)
+	//   - Hyphen (-)
+	fieldRegex = regexp.MustCompile(`^\.[a-zA-Z_\p{L}][a-zA-Z0-9$_\p{L}\-]*$`)
 )
 
 func Parse(str string) (Selector, error) {
@@ -56,6 +68,9 @@ func Parse(str string) (Selector, error) {
 				if err != nil {
 					return nil, newParseError("invalid index", str, col, tok)
 				}
+				if int64(idx) > limits.MaxInt53 || int64(idx) < limits.MinInt53 {
+					return nil, newParseError(fmt.Sprintf("index %d exceeds safe integer bounds", idx), str, col, tok)
+				}
 				sel = append(sel, segment{str: tok, optional: opt, index: idx})
 
 			// explicit field, ["abcd"]
@@ -77,6 +92,9 @@ func Parse(str string) (Selector, error) {
 					if err != nil {
 						return nil, newParseError("invalid slice index", str, col, tok)
 					}
+					if i > limits.MaxInt53 || i < limits.MinInt53 {
+						return nil, newParseError(fmt.Sprintf("slice index %d exceeds safe integer bounds", i), str, col, tok)
+					}
 					rng[0] = i
 				}
 				if splt[1] == "" {
@@ -86,6 +104,9 @@ func Parse(str string) (Selector, error) {
 					if err != nil {
 						return nil, newParseError("invalid slice index", str, col, tok)
 					}
+					if i > limits.MaxInt53 || i < limits.MinInt53 {
+						return nil, newParseError(fmt.Sprintf("slice index %d exceeds safe integer bounds", i), str, col, tok)
+					}
 					rng[1] = i
 				}
 				sel = append(sel, segment{str: tok, optional: opt, slice: rng[:]})
@@ -152,37 +173,37 @@ func tokenize(str string) []string {
 	return toks
 }
 
-type parseerr struct {
+type parseErr struct {
 	msg string
 	src string
 	col int
 	tok string
 }
 
-func (p parseerr) Name() string {
+func (p parseErr) Name() string {
 	return "ParseError"
 }
 
-func (p parseerr) Message() string {
+func (p parseErr) Message() string {
 	return p.msg
 }
 
-func (p parseerr) Column() int {
+func (p parseErr) Column() int {
 	return p.col
 }
 
-func (p parseerr) Error() string {
+func (p parseErr) Error() string {
 	return p.msg
 }
 
-func (p parseerr) Source() string {
+func (p parseErr) Source() string {
 	return p.src
 }
 
-func (p parseerr) Token() string {
+func (p parseErr) Token() string {
 	return p.tok
 }
 
 func newParseError(message string, source string, column int, token string) error {
-	return parseerr{message, source, column, token}
+	return parseErr{message, source, column, token}
 }

pkg/policy/selector/parsing_test.go

@@ -6,6 +6,8 @@ import (
 	"testing"
 
 	"github.com/stretchr/testify/require"
+
+	"github.com/ucan-wg/go-ucan/pkg/policy/limits"
 )
 
 func TestParse(t *testing.T) {
@@ -31,6 +33,29 @@ func TestParse(t *testing.T) {
 		require.Empty(t, sel[0].Slice())
 		require.Equal(t, sel[0].Field(), "foo")
 		require.Empty(t, sel[0].Index())
+
+		sel, err = Parse(".foo_bar")
+		require.NoError(t, err)
+		require.Equal(t, 1, len(sel))
+		require.False(t, sel[0].Identity())
+		require.False(t, sel[0].Optional())
+		require.False(t, sel[0].Iterator())
+		require.Empty(t, sel[0].Slice())
+		require.Equal(t, sel[0].Field(), "foo_bar")
+		require.Empty(t, sel[0].Index())
+
+		sel, err = Parse(".foo-bar")
+		require.NoError(t, err)
+		require.Equal(t, 1, len(sel))
+		require.False(t, sel[0].Identity())
+		require.False(t, sel[0].Optional())
+		require.False(t, sel[0].Iterator())
+		require.Empty(t, sel[0].Slice())
+		require.Equal(t, sel[0].Field(), "foo-bar")
+		require.Empty(t, sel[0].Index())
+
+		sel, err = Parse(".foo*bar")
+		require.ErrorContains(t, err, "invalid segment")
 	})
 
 	t.Run("explicit field", func(t *testing.T) {
@@ -354,7 +379,6 @@ func TestParse(t *testing.T) {
 		str := `.foo.["bar"].[138]?.baz[1:]`
 		sel, err := Parse(str)
 		require.NoError(t, err)
-		printSegments(sel)
 		require.Equal(t, str, sel.String())
 		require.Equal(t, 7, len(sel))
 		require.False(t, sel[0].Identity())
@@ -404,13 +428,11 @@ func TestParse(t *testing.T) {
 	t.Run("non dotted", func(t *testing.T) {
 		_, err := Parse("foo")
 		require.NotNil(t, err)
-		fmt.Println(err)
 	})
 
 	t.Run("non quoted", func(t *testing.T) {
 		_, err := Parse(".[foo]")
 		require.NotNil(t, err)
-		fmt.Println(err)
 	})
 
 	t.Run("slice with negative start and positive end", func(t *testing.T) {
@@ -553,10 +575,67 @@ func TestParse(t *testing.T) {
 		_, err := Parse(".[foo]")
 		require.Error(t, err)
 	})
-}
 
-func printSegments(s Selector) {
-	for i, seg := range s {
-		fmt.Printf("%d: %s\n", i, seg.String())
-	}
+	t.Run("extended field names", func(t *testing.T) {
+		validFields := []string{
+			".basic",
+			".user_name",
+			".user-name",
+			".userName$special",
+			".αβγ",        // Greek letters
+			".użytkownik", // Polish characters
+			".用户",         // Chinese characters
+			".사용자",        // Korean characters
+			"._private",
+			".number123",
+			".camelCase",
+			".snake_case",
+			".kebab-case",
+			".mixed_kebab-case",
+			".with$dollar",
+			".MIXED_Case_123",
+			".unicodeø",
+		}
+
+		for _, field := range validFields {
+			sel, err := Parse(field)
+			require.NoError(t, err, "field: %s", field)
+			require.NotNil(t, sel)
+		}
+
+		invalidFields := []string{
+			".123number",         // Can't start with digit
+			".@special",          // @ not allowed
+			".space name",        // No spaces
+			".#hashtag",          // No #
+			".name!",             // No !
+			".{brackets}",        // No brackets
+			".name/with/slashes", // No slashes
+		}
+
+		for _, field := range invalidFields {
+			sel, err := Parse(field)
+			require.Error(t, err, "field: %s", field)
+			require.Nil(t, sel)
+		}
+	})
+
+	t.Run("integer overflow", func(t *testing.T) {
+		sel, err := Parse(fmt.Sprintf(".[%d]", limits.MaxInt53+1))
+		require.Error(t, err)
+		require.Nil(t, sel)
+
+		sel, err = Parse(fmt.Sprintf(".[%d]", limits.MinInt53-1))
+		require.Error(t, err)
+		require.Nil(t, sel)
+
+		// Test slice overflow
+		sel, err = Parse(fmt.Sprintf(".[%d:42]", limits.MaxInt53+1))
+		require.Error(t, err)
+		require.Nil(t, sel)
+
+		sel, err = Parse(fmt.Sprintf(".[1:%d]", limits.MaxInt53+1))
+		require.Error(t, err)
+		require.Nil(t, sel)
+	})
 }

pkg/policy/selector/selector.go

@@ -19,7 +19,7 @@ type Selector []segment
 // Select perform the selection described by the selector on the input IPLD DAG.
 // Select can return:
 //   - exactly one matched IPLD node
-//   - a resolutionerr error if not being able to resolve to a node
+//   - a resolutionErr error if not being able to resolve to a node
 //   - nil and no errors, if the selector couldn't match on an optional segment (with ?).
 func (s Selector) Select(subject ipld.Node) (ipld.Node, error) {
 	return resolve(s, subject, nil)
@@ -266,19 +266,32 @@ func resolveSliceIndices(slice []int64, length int64) (start int64, end int64) {
 	case slice[0] == math.MinInt:
 		start = 0
 	case slice[0] < 0:
-		start = length + slice[0]
+		// Check for potential overflow before adding
+		if -slice[0] > length {
+			start = 0
+		} else {
+			start = length + slice[0]
+		}
 	}
+
 	switch {
 	case slice[1] == math.MaxInt:
 		end = length
 	case slice[1] < 0:
-		end = length + slice[1]
+		// Check for potential overflow before adding
+		if -slice[1] > length {
+			end = 0
+		} else {
+			end = length + slice[1]
+		}
 	}
 
 	// backward iteration is not allowed, shortcut to an empty result
 	if start >= end {
 		start, end = 0, 0
+		return
 	}
+
 	// clamp out of bound
 	if start < 0 {
 		start = 0
@@ -286,11 +299,14 @@ func resolveSliceIndices(slice []int64, length int64) (start int64, end int64) {
 	if start > length {
 		start = length
 	}
+	if end < 0 {
+		end = 0
+	}
 	if end > length {
 		end = length
 	}
 
-	return start, end
+	return
 }
 
 func kindString(n datamodel.Node) string {
@@ -300,27 +316,27 @@ func kindString(n datamodel.Node) string {
 	return n.Kind().String()
 }
 
-type resolutionerr struct {
+type resolutionErr struct {
 	msg string
 	at  []string
 }
 
-func (r resolutionerr) Name() string {
+func (r resolutionErr) Name() string {
 	return "ResolutionError"
 }
 
-func (r resolutionerr) Message() string {
+func (r resolutionErr) Message() string {
 	return fmt.Sprintf("can not resolve path: .%s", strings.Join(r.at, "."))
 }
 
-func (r resolutionerr) At() []string {
+func (r resolutionErr) At() []string {
 	return r.at
 }
 
-func (r resolutionerr) Error() string {
+func (r resolutionErr) Error() string {
 	return r.Message()
 }
 
 func newResolutionError(message string, at []string) error {
-	return resolutionerr{message, at}
+	return resolutionErr{message, at}
 }

pkg/policy/selector/selector_test.go

@@ -2,7 +2,7 @@ package selector
 
 import (
 	"errors"
-	"fmt"
+	"math"
 	"strings"
 	"testing"
 
@@ -13,7 +13,6 @@ import (
 	"github.com/ipld/go-ipld-prime/must"
 	basicnode "github.com/ipld/go-ipld-prime/node/basic"
 	"github.com/ipld/go-ipld-prime/node/bindnode"
-	"github.com/ipld/go-ipld-prime/printer"
 	"github.com/stretchr/testify/require"
 )
 
@@ -87,8 +86,6 @@ func TestSelect(t *testing.T) {
 		require.NoError(t, err)
 		require.NotEmpty(t, res)
 
-		fmt.Println(printer.Sprint(res))
-
 		age := must.Int(must.Node(res.LookupByString("age")))
 		require.Equal(t, int64(alice.Age), age)
 	})
@@ -101,8 +98,6 @@ func TestSelect(t *testing.T) {
 		require.NoError(t, err)
 		require.NotEmpty(t, res)
 
-		fmt.Println(printer.Sprint(res))
-
 		name := must.String(res)
 		require.Equal(t, alice.Name.First, name)
 
@@ -110,8 +105,6 @@ func TestSelect(t *testing.T) {
 		require.NoError(t, err)
 		require.NotEmpty(t, res)
 
-		fmt.Println(printer.Sprint(res))
-
 		name = must.String(res)
 		require.Equal(t, bob.Name.First, name)
 	})
@@ -124,8 +117,6 @@ func TestSelect(t *testing.T) {
 		require.NoError(t, err)
 		require.NotEmpty(t, res)
 
-		fmt.Println(printer.Sprint(res))
-
 		name := must.String(res)
 		require.Equal(t, *alice.Name.Middle, name)
 
@@ -142,9 +133,7 @@ func TestSelect(t *testing.T) {
 		require.Error(t, err)
 		require.Empty(t, res)
 
-		fmt.Println(err)
-
-		require.ErrorAs(t, err, &resolutionerr{}, "error should be a resolution error")
+		require.ErrorAs(t, err, &resolutionErr{}, "error should be a resolution error")
 	})
 
 	t.Run("optional not exists", func(t *testing.T) {
@@ -164,8 +153,6 @@ func TestSelect(t *testing.T) {
 		require.NoError(t, err)
 		require.NotEmpty(t, res)
 
-		fmt.Println(printer.Sprint(res))
-
 		iname := must.String(must.Node(must.Node(res.LookupByIndex(0)).LookupByString("name")))
 		require.Equal(t, alice.Interests[0].Name, iname)
 
@@ -364,9 +351,63 @@ func FuzzParseAndSelect(f *testing.F) {
 
 		// look for panic()
 		_, err = sel.Select(node)
-		if err != nil && !errors.As(err, &resolutionerr{}) {
+		if err != nil && !errors.As(err, &resolutionErr{}) {
 			// not normal, we should only have resolution errors
 			t.Fatal(err)
 		}
 	})
 }
+
+func TestResolveSliceIndices(t *testing.T) {
+	tests := []struct {
+		name      string
+		slice     []int64
+		length    int64
+		wantStart int64
+		wantEnd   int64
+	}{
+		{
+			name:      "normal case",
+			slice:     []int64{1, 3},
+			length:    5,
+			wantStart: 1,
+			wantEnd:   3,
+		},
+		{
+			name:      "negative indices",
+			slice:     []int64{-2, -1},
+			length:    5,
+			wantStart: 3,
+			wantEnd:   4,
+		},
+		{
+			name:      "overflow protection negative start",
+			slice:     []int64{math.MinInt64, 3},
+			length:    5,
+			wantStart: 0,
+			wantEnd:   3,
+		},
+		{
+			name:      "overflow protection negative end",
+			slice:     []int64{0, math.MinInt64},
+			length:    5,
+			wantStart: 0,
+			wantEnd:   0,
+		},
+		{
+			name:      "max bounds",
+			slice:     []int64{0, math.MaxInt64},
+			length:    5,
+			wantStart: 0,
+			wantEnd:   5,
+		},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			start, end := resolveSliceIndices(tt.slice, tt.length)
+			require.Equal(t, tt.wantStart, start)
+			require.Equal(t, tt.wantEnd, end)
+		})
+	}
+}

pkg/policy/selector/supported_test.go

@@ -1,15 +1,12 @@
 package selector_test
 
 import (
-	"bytes"
 	"strings"
 	"testing"
 
 	"github.com/ipld/go-ipld-prime"
 	"github.com/ipld/go-ipld-prime/codec/dagjson"
-	"github.com/ipld/go-ipld-prime/datamodel"
 	basicnode "github.com/ipld/go-ipld-prime/node/basic"
-	"github.com/stretchr/testify/assert"
 	"github.com/stretchr/testify/require"
 
 	"github.com/ucan-wg/go-ucan/pkg/policy/selector"
@@ -55,7 +52,7 @@ func TestSupportedForms(t *testing.T) {
 			require.NotNil(t, res)
 
 			exp := makeNode(t, tc.Output)
-			equalIPLD(t, exp, res)
+			require.True(t, ipld.DeepEqual(exp, res))
 		})
 	}
 
@@ -106,23 +103,6 @@ func TestSupportedForms(t *testing.T) {
 	}
 }
 
-func equalIPLD(t *testing.T, expected datamodel.Node, actual datamodel.Node) bool {
-	t.Helper()
-
-	exp, act := &bytes.Buffer{}, &bytes.Buffer{}
-	if err := dagjson.Encode(expected, exp); err != nil {
-		return assert.Fail(t, "Failed to encode json for expected IPLD node")
-	}
-
-	if err := dagjson.Encode(actual, act); err != nil {
-		return assert.Fail(t, "Failed to encode JSON for actual IPLD node")
-	}
-
-	require.JSONEq(t, exp.String(), act.String())
-
-	return true
-}
-
 func makeNode(t *testing.T, dagJsonInput string) ipld.Node {
 	t.Helper()
 

pkg/secretbox/secretbox.go

@@ -0,0 +1,90 @@
+package secretbox
+
+import (
+	"crypto/rand"
+	"errors"
+	"fmt"
+	"io"
+
+	"golang.org/x/crypto/nacl/secretbox"
+)
+
+const keySize = 32 // secretbox allows only 32-byte keys
+
+var ErrShortCipherText = errors.New("ciphertext too short")
+var ErrNoEncryptionKey = errors.New("encryption key is required")
+var ErrInvalidKeySize = errors.New("invalid key size: must be 32 bytes")
+var ErrZeroKey = errors.New("encryption key cannot be all zeros")
+
+// GenerateKey generates a random 32-byte key to be used by EncryptWithKey and DecryptWithKey
+func GenerateKey() ([]byte, error) {
+	key := make([]byte, keySize)
+	if _, err := io.ReadFull(rand.Reader, key); err != nil {
+		return nil, fmt.Errorf("failed to generate key: %w", err)
+	}
+	return key, nil
+}
+
+// EncryptWithKey encrypts data using NaCl's secretbox with the provided key.
+// 40 bytes of overhead (24-byte nonce + 16-byte MAC) are added to the plaintext size.
+func EncryptWithKey(data, key []byte) ([]byte, error) {
+	if err := validateKey(key); err != nil {
+		return nil, err
+	}
+
+	var secretKey [keySize]byte
+	copy(secretKey[:], key)
+
+	// Generate 24 bytes of random data as nonce
+	var nonce [24]byte
+	if _, err := io.ReadFull(rand.Reader, nonce[:]); err != nil {
+		return nil, err
+	}
+
+	// Encrypt and authenticate data
+	encrypted := secretbox.Seal(nonce[:], data, &nonce, &secretKey)
+	return encrypted, nil
+}
+
+// DecryptStringWithKey decrypts data using secretbox with the provided key
+func DecryptStringWithKey(data, key []byte) ([]byte, error) {
+	if err := validateKey(key); err != nil {
+		return nil, err
+	}
+
+	if len(data) < 24 {
+		return nil, ErrShortCipherText
+	}
+
+	var secretKey [keySize]byte
+	copy(secretKey[:], key)
+
+	var nonce [24]byte
+	copy(nonce[:], data[:24])
+
+	decrypted, ok := secretbox.Open(nil, data[24:], &nonce, &secretKey)
+	if !ok {
+		return nil, errors.New("decryption failed")
+	}
+
+	return decrypted, nil
+}
+
+func validateKey(key []byte) error {
+	if key == nil {
+		return ErrNoEncryptionKey
+	}
+
+	if len(key) != keySize {
+		return ErrInvalidKeySize
+	}
+
+	// check if key is all zeros
+	for _, b := range key {
+		if b != 0 {
+			return nil
+		}
+	}
+
+	return ErrZeroKey
+}

pkg/secretbox/secretbox_test.go

@@ -0,0 +1,144 @@
+package secretbox
+
+import (
+	"bytes"
+	"crypto/rand"
+	"testing"
+
+	"github.com/stretchr/testify/require"
+)
+
+func TestSecretBoxEncryption(t *testing.T) {
+	t.Parallel()
+
+	key := make([]byte, keySize) // generate random 32-byte key
+	_, errKey := rand.Read(key)
+	require.NoError(t, errKey)
+
+	tests := []struct {
+		name    string
+		data    []byte
+		key     []byte
+		wantErr error
+	}{
+		{
+			name: "valid encryption/decryption",
+			data: []byte("hello world"),
+			key:  key,
+		},
+		{
+			name:    "nil key returns error",
+			data:    []byte("hello world"),
+			key:     nil,
+			wantErr: ErrNoEncryptionKey,
+		},
+		{
+			name: "empty data",
+			data: []byte{},
+			key:  key,
+		},
+		{
+			name:    "invalid key size",
+			data:    []byte("hello world"),
+			key:     make([]byte, 16), // Only 32 bytes allowed now
+			wantErr: ErrInvalidKeySize,
+		},
+		{
+			name:    "zero key returns error",
+			data:    []byte("hello world"),
+			key:     make([]byte, keySize),
+			wantErr: ErrZeroKey,
+		},
+	}
+
+	for _, tt := range tests {
+		tt := tt
+		t.Run(tt.name, func(t *testing.T) {
+			t.Parallel()
+
+			encrypted, err := EncryptWithKey(tt.data, tt.key)
+			if tt.wantErr != nil {
+				require.ErrorIs(t, err, tt.wantErr)
+				return
+			}
+			require.NoError(t, err)
+
+			// Verify encrypted data is different and includes nonce
+			require.Greater(t, len(encrypted), 24) // At least nonce size
+			if len(tt.data) > 0 {
+				require.NotEqual(t, tt.data, encrypted[24:]) // Ignore nonce prefix
+			}
+
+			decrypted, err := DecryptStringWithKey(encrypted, tt.key)
+			require.NoError(t, err)
+			require.True(t, bytes.Equal(tt.data, decrypted))
+		})
+	}
+}
+
+func TestDecryptionErrors(t *testing.T) {
+	t.Parallel()
+
+	key := make([]byte, keySize)
+	_, err := rand.Read(key)
+	require.NoError(t, err)
+
+	// Create valid encrypted data for tampering tests
+	validData := []byte("test message")
+	encrypted, err := EncryptWithKey(validData, key)
+	require.NoError(t, err)
+
+	tests := []struct {
+		name   string
+		data   []byte
+		key    []byte
+		errMsg string
+	}{
+		{
+			name:   "short ciphertext",
+			data:   make([]byte, 23), // Less than nonce size
+			key:    key,
+			errMsg: "ciphertext too short",
+		},
+		{
+			name:   "invalid ciphertext",
+			data:   make([]byte, 24), // Just nonce size
+			key:    key,
+			errMsg: "decryption failed",
+		},
+		{
+			name:   "tampered ciphertext",
+			data:   tamperWithBytes(encrypted),
+			key:    key,
+			errMsg: "decryption failed",
+		},
+		{
+			name:   "missing key",
+			data:   encrypted,
+			key:    nil,
+			errMsg: "encryption key is required",
+		},
+	}
+
+	for _, tt := range tests {
+		tt := tt
+		t.Run(tt.name, func(t *testing.T) {
+			t.Parallel()
+
+			_, err := DecryptStringWithKey(tt.data, tt.key)
+			require.Error(t, err)
+			require.Contains(t, err.Error(), tt.errMsg)
+		})
+	}
+}
+
+// tamperWithBytes modifies a byte in the encrypted data to simulate tampering
+func tamperWithBytes(data []byte) []byte {
+	if len(data) < 25 { // Need at least nonce + 1 byte
+		return data
+	}
+	tampered := make([]byte, len(data))
+	copy(tampered, data)
+	tampered[24] ^= 0x01 // Modify first byte after nonce
+	return tampered
+}

token/delegation/delegation.go

@@ -10,17 +10,18 @@ package delegation
 // TODO: change the "delegation" link above when the specification is merged
 
 import (
-	"crypto/rand"
+	"encoding/base64"
 	"errors"
 	"fmt"
+	"strings"
 	"time"
 
-	"github.com/libp2p/go-libp2p/core/crypto"
-
 	"github.com/ucan-wg/go-ucan/did"
 	"github.com/ucan-wg/go-ucan/pkg/command"
 	"github.com/ucan-wg/go-ucan/pkg/meta"
 	"github.com/ucan-wg/go-ucan/pkg/policy"
+	"github.com/ucan-wg/go-ucan/token/internal/nonce"
+	"github.com/ucan-wg/go-ucan/token/internal/parse"
 )
 
 // Token is an immutable type that holds the fields of a UCAN delegation.
@@ -45,21 +46,15 @@ type Token struct {
 	expiration *time.Time
 }
 
-// New creates a validated Token from the provided parameters and options.
+// New creates a validated delegation Token from the provided parameters and options.
+// This is typically used to delegate a given power to another agent.
 //
-// When creating a delegated token, the Issuer's (iss) DID is assembed
-// using the public key associated with the private key sent as the first
-// parameter.
-func New(privKey crypto.PrivKey, aud did.DID, cmd command.Command, pol policy.Policy, opts ...Option) (*Token, error) {
-	iss, err := did.FromPrivKey(privKey)
-	if err != nil {
-		return nil, err
-	}
-
+// You can read it as "(issuer) allows (audience) to perform (cmd+pol) on (subject)".
+func New(iss did.DID, aud did.DID, cmd command.Command, pol policy.Policy, sub did.DID, opts ...Option) (*Token, error) {
 	tkn := &Token{
 		issuer:   iss,
 		audience: aud,
-		subject:  did.Undef,
+		subject:  sub,
 		command:  cmd,
 		policy:   pol,
 		meta:     meta.NewMeta(),
@@ -72,8 +67,9 @@ func New(privKey crypto.PrivKey, aud did.DID, cmd command.Command, pol policy.Po
 		}
 	}
 
+	var err error
 	if len(tkn.nonce) == 0 {
-		tkn.nonce, err = generateNonce()
+		tkn.nonce, err = nonce.Generate()
 		if err != nil {
 			return nil, err
 		}
@@ -86,21 +82,27 @@ func New(privKey crypto.PrivKey, aud did.DID, cmd command.Command, pol policy.Po
 	return tkn, nil
 }
 
-// Root creates a validated UCAN delegation Token from the provided
-// parameters and options.
+// Root creates a validated UCAN delegation Token from the provided parameters and options.
+// This is typically used to create and give power to an agent.
 //
-// When creating a root token, both the Issuer's (iss) and Subject's
-// (sub) DIDs are assembled from the public key associated with the
-// private key passed as the first argument.
-func Root(privKey crypto.PrivKey, aud did.DID, cmd command.Command, pol policy.Policy, opts ...Option) (*Token, error) {
-	sub, err := did.FromPrivKey(privKey)
-	if err != nil {
-		return nil, err
-	}
+// You can read it as "(issuer) allows (audience) to perform (cmd+pol) on itself".
+func Root(iss did.DID, aud did.DID, cmd command.Command, pol policy.Policy, opts ...Option) (*Token, error) {
+	return New(iss, aud, cmd, pol, iss, opts...)
+}
 
-	opts = append(opts, WithSubject(sub))
-
-	return New(privKey, aud, cmd, pol, opts...)
+// Powerline creates a validated UCAN delegation Token from the provided parameters and options.
+//
+// Powerline is a pattern for automatically delegating all future delegations to another agent regardless of Subject.
+// This is a very powerful pattern, use it only if you understand it.
+// Powerline delegations MUST NOT be used as the root delegation to a resource
+//
+// A very common use case for Powerline is providing a stable DID across multiple agents (e.g. representing a user with
+// multiple devices). This enables the automatic sharing of authority across their devices without needing to share keys
+// or set up a threshold scheme. It is also flexible, since a Powerline delegation MAY be revoked.
+//
+// You can read it as "(issuer) allows (audience) to perform (cmd+pol) on anything".
+func Powerline(iss did.DID, aud did.DID, cmd command.Command, pol policy.Policy, opts ...Option) (*Token, error) {
+	return New(iss, aud, cmd, pol, did.Undef, opts...)
 }
 
 // Issuer returns the did.DID representing the Token's issuer.
@@ -152,6 +154,60 @@ func (t *Token) Expiration() *time.Time {
 	return t.expiration
 }
 
+// IsRoot tells if the token is a root delegation.
+func (t *Token) IsRoot() bool {
+	return t.issuer == t.subject
+}
+
+// IsPowerline tells if the token is a powerline delegation.
+func (t *Token) IsPowerline() bool {
+	return t.subject == did.Undef
+}
+
+// IsValidNow verifies that the token can be used at the current time, based on expiration or "not before" fields.
+// This does NOT do any other kind of verifications.
+func (t *Token) IsValidNow() bool {
+	return t.IsValidAt(time.Now())
+}
+
+// IsValidNow verifies that the token can be used at the given time, based on expiration or "not before" fields.
+// This does NOT do any other kind of verifications.
+func (t *Token) IsValidAt(ti time.Time) bool {
+	if t.expiration != nil && ti.After(*t.expiration) {
+		return false
+	}
+	if t.notBefore != nil && ti.Before(*t.notBefore) {
+		return false
+	}
+	return true
+}
+
+func (t *Token) String() string {
+	var res strings.Builder
+
+	var kind string
+	switch {
+	case t.issuer == t.subject:
+		kind = " (root delegation)"
+	case t.subject == did.Undef:
+		kind = " (powerline delegation)"
+	default:
+		kind = " (normal delegation)"
+	}
+
+	res.WriteString(fmt.Sprintf("Issuer: %s\n", t.Issuer()))
+	res.WriteString(fmt.Sprintf("Audience: %s\n", t.Audience()))
+	res.WriteString(fmt.Sprintf("Subject: %s%s\n", t.Subject(), kind))
+	res.WriteString(fmt.Sprintf("Command: %s\n", t.Command()))
+	res.WriteString(fmt.Sprintf("Policy: %s\n", t.Policy()))
+	res.WriteString(fmt.Sprintf("Nonce: %s\n", base64.StdEncoding.EncodeToString(t.Nonce())))
+	res.WriteString(fmt.Sprintf("Meta: %s\n", t.Meta()))
+	res.WriteString(fmt.Sprintf("NotBefore: %v\n", t.NotBefore()))
+	res.WriteString(fmt.Sprintf("Expiration: %v", t.Expiration()))
+
+	return res.String()
+}
+
 func (t *Token) validate() error {
 	var errs error
 
@@ -184,27 +240,19 @@ func tokenFromModel(m tokenPayloadModel) (*Token, error) {
 		return nil, fmt.Errorf("parse iss: %w", err)
 	}
 
-	tkn.audience, err = did.Parse(m.Aud)
-	if err != nil {
+	if tkn.audience, err = did.Parse(m.Aud); err != nil {
 		return nil, fmt.Errorf("parse audience: %w", err)
 	}
 
-	if m.Sub != nil {
-		tkn.subject, err = did.Parse(*m.Sub)
-		if err != nil {
-			return nil, fmt.Errorf("parse subject: %w", err)
-		}
-	} else {
-		tkn.subject = did.Undef
+	if tkn.subject, err = parse.OptionalDID(m.Sub); err != nil {
+		return nil, fmt.Errorf("parse subject: %w", err)
 	}
 
-	tkn.command, err = command.Parse(m.Cmd)
-	if err != nil {
+	if tkn.command, err = command.Parse(m.Cmd); err != nil {
 		return nil, fmt.Errorf("parse command: %w", err)
 	}
 
-	tkn.policy, err = policy.FromIPLD(m.Pol)
-	if err != nil {
+	if tkn.policy, err = policy.FromIPLD(m.Pol); err != nil {
 		return nil, fmt.Errorf("parse policy: %w", err)
 	}
 
@@ -214,15 +262,18 @@ func tokenFromModel(m tokenPayloadModel) (*Token, error) {
 	tkn.nonce = m.Nonce
 
 	tkn.meta = m.Meta
-
-	if m.Nbf != nil {
-		t := time.Unix(*m.Nbf, 0)
-		tkn.notBefore = &t
+	if tkn.meta == nil {
+		tkn.meta = meta.NewMeta()
 	}
 
-	if m.Exp != nil {
-		t := time.Unix(*m.Exp, 0)
-		tkn.expiration = &t
+	tkn.notBefore, err = parse.OptionalTimestamp(m.Nbf)
+	if err != nil {
+		return nil, fmt.Errorf("parse notBefore: %w", err)
+	}
+
+	tkn.expiration, err = parse.OptionalTimestamp(m.Exp)
+	if err != nil {
+		return nil, fmt.Errorf("parse expiration: %w", err)
 	}
 
 	if err := tkn.validate(); err != nil {
@@ -231,14 +282,3 @@ func tokenFromModel(m tokenPayloadModel) (*Token, error) {
 
 	return &tkn, nil
 }
-
-// generateNonce creates a 12-byte random nonce.
-// TODO: some crypto scheme require more, is that our case?
-func generateNonce() ([]byte, error) {
-	res := make([]byte, 12)
-	_, err := rand.Read(res)
-	if err != nil {
-		return nil, err
-	}
-	return res, nil
-}

token/delegation/delegation_test.go

@@ -1,14 +1,14 @@
 package delegation_test
 
 import (
+	"encoding/base64"
 	"testing"
 	"time"
 
-	"github.com/libp2p/go-libp2p/core/crypto"
 	"github.com/stretchr/testify/require"
 	"gotest.tools/v3/golden"
 
-	"github.com/ucan-wg/go-ucan/did"
+	"github.com/ucan-wg/go-ucan/did/didtest"
 	"github.com/ucan-wg/go-ucan/pkg/command"
 	"github.com/ucan-wg/go-ucan/pkg/policy"
 	"github.com/ucan-wg/go-ucan/token/delegation"
@@ -17,67 +17,28 @@ import (
 const (
 	nonce = "6roDhGi0kiNriQAz7J3d+bOeoI/tj8ENikmQNbtjnD0"
 
-	AudiencePrivKeyCfg = "CAESQL1hvbXpiuk2pWr/XFbfHJcZNpJ7S90iTA3wSCTc/BPRneCwPnCZb6c0vlD6ytDWqaOt0HEOPYnqEpnzoBDprSM="
-	AudienceDID        = "did:key:z6Mkq5YmbJcTrPExNDi26imrTCpKhepjBFBSHqrBDN2ArPkv"
-
-	issuerPrivKeyCfg = "CAESQLSql38oDmQXIihFFaYIjb73mwbPsc7MIqn4o8PN4kRNnKfHkw5gRP1IV9b6d0estqkZayGZ2vqMAbhRixjgkDU="
-	issuerDID        = "did:key:z6Mkpzn2n3ZGT2VaqMGSQC3tzmzV4TS9S71iFsDXE1WnoNH2"
-
-	subjectPrivKeyCfg = "CAESQL9RtjZ4dQBeXtvDe53UyvslSd64kSGevjdNiA1IP+hey5i/3PfRXSuDr71UeJUo1fLzZ7mGldZCOZL3gsIQz5c="
-	subjectDID        = "did:key:z6MktA1uBdCpq4uJBqE9jjMiLyxZBg9a6xgPPKJjMqss6Zc2"
-	subJectCmd        = "/foo/bar"
-	subjectPol        = `
+	subJectCmd = "/foo/bar"
+	subjectPol = `
 [
-	[
-		"==",
-		".status",
-		"draft"
-	],
-	[
-		"all",
-		".reviewer",
-		[
-			"like",
-			".email",
-			"*@example.com"
-		]
-	],
-	[
-		"any",
-		".tags",
-		[
-			"or",
-			[
-				[
-					"==",
-					".",
-					"news"
-				],
-				[
-					"==",
-					".",
-					"press"
-				]
-			]
-		]
-	]
+  ["==", ".status", "draft"],
+  ["all", ".reviewer",
+    ["like", ".email", "*@example.com"]
+  ],
+  ["any", ".tags",
+    ["or", [
+      ["==", ".", "news"],
+      ["==", ".", "press"]
+    ]]
+  ]
 ]
 `
 
-	newCID  = "zdpuAn9JgGPvnt2WCmTaKktZdbuvcVGTg9bUT5kQaufwUtZ6e"
-	rootCID = "zdpuAkgGmUp5JrXvehGuuw9JA8DLQKDaxtK3R8brDQQVC2i5X"
+	aesKey = "xQklMmNTnVrmaPBq/0pwV5fEwuv/iClF5HWak9MsgI8="
 )
 
 func TestConstructors(t *testing.T) {
 	t.Parallel()
 
-	privKey := privKey(t, issuerPrivKeyCfg)
-
-	aud, err := did.Parse(AudienceDID)
-
-	sub, err := did.Parse(subjectDID)
-	require.NoError(t, err)
-
 	cmd, err := command.Parse(subJectCmd)
 	require.NoError(t, err)
 
@@ -88,19 +49,19 @@ func TestConstructors(t *testing.T) {
 	require.NoError(t, err)
 
 	t.Run("New", func(t *testing.T) {
-		tkn, err := delegation.New(privKey, aud, cmd, pol,
+		tkn, err := delegation.New(didtest.PersonaAlice.DID(), didtest.PersonaBob.DID(), cmd, pol, didtest.PersonaCarol.DID(),
 			delegation.WithNonce([]byte(nonce)),
-			delegation.WithSubject(sub),
 			delegation.WithExpiration(exp),
 			delegation.WithMeta("foo", "fooo"),
 			delegation.WithMeta("bar", "barr"),
 		)
 		require.NoError(t, err)
 
-		data, err := tkn.ToDagJson(privKey)
-		require.NoError(t, err)
+		require.False(t, tkn.IsRoot())
+		require.False(t, tkn.IsPowerline())
 
-		t.Log(string(data))
+		data, err := tkn.ToDagJson(didtest.PersonaAlice.PrivKey())
+		require.NoError(t, err)
 
 		golden.Assert(t, string(data), "new.dagjson")
 	})
@@ -108,7 +69,7 @@ func TestConstructors(t *testing.T) {
 	t.Run("Root", func(t *testing.T) {
 		t.Parallel()
 
-		tkn, err := delegation.Root(privKey, aud, cmd, pol,
+		tkn, err := delegation.Root(didtest.PersonaAlice.DID(), didtest.PersonaBob.DID(), cmd, pol,
 			delegation.WithNonce([]byte(nonce)),
 			delegation.WithExpiration(exp),
 			delegation.WithMeta("foo", "fooo"),
@@ -116,21 +77,132 @@ func TestConstructors(t *testing.T) {
 		)
 		require.NoError(t, err)
 
-		data, err := tkn.ToDagJson(privKey)
-		require.NoError(t, err)
+		require.True(t, tkn.IsRoot())
+		require.False(t, tkn.IsPowerline())
 
-		t.Log(string(data))
+		data, err := tkn.ToDagJson(didtest.PersonaAlice.PrivKey())
+		require.NoError(t, err)
 
 		golden.Assert(t, string(data), "root.dagjson")
 	})
+
+	t.Run("Powerline", func(t *testing.T) {
+		t.Parallel()
+
+		tkn, err := delegation.Powerline(didtest.PersonaAlice.DID(), didtest.PersonaBob.DID(), cmd, pol,
+			delegation.WithNonce([]byte(nonce)),
+			delegation.WithExpiration(exp),
+			delegation.WithMeta("foo", "fooo"),
+			delegation.WithMeta("bar", "barr"),
+		)
+		require.NoError(t, err)
+
+		require.False(t, tkn.IsRoot())
+		require.True(t, tkn.IsPowerline())
+
+		data, err := tkn.ToDagJson(didtest.PersonaAlice.PrivKey())
+		require.NoError(t, err)
+
+		golden.Assert(t, string(data), "powerline.dagjson")
+	})
 }
 
-func privKey(t require.TestingT, privKeyCfg string) crypto.PrivKey {
-	privKeyMar, err := crypto.ConfigDecodeKey(privKeyCfg)
+func TestEncryptedMeta(t *testing.T) {
+	t.Parallel()
+
+	cmd, err := command.Parse(subJectCmd)
+	require.NoError(t, err)
+	pol, err := policy.FromDagJson(subjectPol)
 	require.NoError(t, err)
 
-	privKey, err := crypto.UnmarshalPrivateKey(privKeyMar)
+	encryptionKey, err := base64.StdEncoding.DecodeString(aesKey)
 	require.NoError(t, err)
+	require.Len(t, encryptionKey, 32)
 
-	return privKey
+	tests := []struct {
+		name        string
+		key         string
+		value       string
+		expectError bool
+	}{
+		{
+			name:  "simple string",
+			key:   "secret1",
+			value: "hello world",
+		},
+		{
+			name:  "empty string",
+			key:   "secret2",
+			value: "",
+		},
+		{
+			name:  "special characters",
+			key:   "secret3",
+			value: "!@#$%^&*()_+-=[]{}|;:,.<>?",
+		},
+		{
+			name:  "unicode characters",
+			key:   "secret4",
+			value: "Hello, 世界! 👋",
+		},
+	}
+
+	for _, tt := range tests {
+		tt := tt
+		t.Run(tt.name, func(t *testing.T) {
+			t.Parallel()
+
+			tkn, err := delegation.Root(didtest.PersonaAlice.DID(), didtest.PersonaBob.DID(), cmd, pol,
+				delegation.WithEncryptedMetaString(tt.key, tt.value, encryptionKey),
+			)
+			require.NoError(t, err)
+
+			data, err := tkn.ToDagCbor(didtest.PersonaAlice.PrivKey())
+			require.NoError(t, err)
+
+			decodedTkn, _, err := delegation.FromSealed(data)
+			require.NoError(t, err)
+
+			_, err = decodedTkn.Meta().GetString(tt.key)
+			require.Error(t, err)
+
+			decrypted, err := decodedTkn.Meta().GetEncryptedString(tt.key, encryptionKey)
+			require.NoError(t, err)
+			// Verify the decrypted value is equal to the original
+			require.Equal(t, tt.value, decrypted)
+
+			// Try to decrypt with wrong key
+			wrongKey := make([]byte, 32)
+			_, err = decodedTkn.Meta().GetEncryptedString(tt.key, wrongKey)
+			require.Error(t, err)
+		})
+	}
+
+	t.Run("multiple encrypted values in the same token", func(t *testing.T) {
+		values := map[string]string{
+			"secret1": "value1",
+			"secret2": "value2",
+			"secret3": "value3",
+		}
+		var opts []delegation.Option
+		for k, v := range values {
+			opts = append(opts, delegation.WithEncryptedMetaString(k, v, encryptionKey))
+		}
+
+		// Create token with multiple encrypted values
+		tkn, err := delegation.Root(didtest.PersonaAlice.DID(), didtest.PersonaBob.DID(), cmd, pol, opts...)
+		require.NoError(t, err)
+
+		data, err := tkn.ToDagCbor(didtest.PersonaAlice.PrivKey())
+		require.NoError(t, err)
+
+		decodedTkn, _, err := delegation.FromSealed(data)
+		require.NoError(t, err)
+
+		for k, v := range values {
+			decrypted, err := decodedTkn.Meta().GetEncryptedString(k, encryptionKey)
+			require.NoError(t, err)
+			require.Equal(t, v, decrypted)
+		}
+	})
 }

token/delegation/delegationtest/README.md

@@ -0,0 +1,5 @@
+# delegationtest
+
+See the package documentation for instructions on how to use the generated
+tokens as well as information on how to regenerate the code if changes have
+been made.

token/delegation/delegationtest/doc.go

@@ -0,0 +1,33 @@
+// Package delegationtest provides a set of pre-built delegation tokens
+// for a variety of test cases.
+//
+// For all delegation tokens, the name of the delegation token is the
+// Issuer appended with the Audience.  The tokens are generated so that
+// an invocation can be created for any didtest.Persona.
+//
+// Delegation proof-chain names contain each didtest.Persona name in
+// order starting with the root delegation (which will always be generated
+// by Alice). This is the opposite of the list of cic.Cids that represent the
+// proof chain.
+//
+// For both the generated delegation tokens granted to Carol's Persona and
+// the proof chains containing Carol's delegations to Dan, if there is no
+// suffix, the proof chain will be deemed valid.  If there is a suffix, it
+// will consist of either the word "Valid" or "Invalid" and the name of the
+// field that has been altered. Only optional fields will generate proof
+// chains with Valid suffixes.
+//
+// If changes are made to the list of Personas included in the chain, or
+// in the variants that are specified, the generated Go file and delegation
+// tokens stored in the data/ directory should be regenerated by running
+// the following command in this directory:
+//
+//	cd generator && go run .
+//
+// Generated delegation Tokens are stored in the data/ directory and loaded
+// into the delegation.Loader.
+// Generated references to these tokens and the tokens themselves are
+// created in the token_gen.go file. See /token/invocation/invocation_test.go
+// for an example of how these delegation tokens and proof-chains can
+// be used during testing.
+package delegationtest

token/delegation/delegationtest/generator/generator.go

@@ -0,0 +1,275 @@
+package main
+
+import (
+	"bytes"
+	"fmt"
+	"go/format"
+	"os"
+	"path/filepath"
+	"slices"
+	"time"
+
+	"github.com/ipfs/go-cid"
+	"github.com/libp2p/go-libp2p/core/crypto"
+
+	"github.com/ucan-wg/go-ucan/did"
+	"github.com/ucan-wg/go-ucan/did/didtest"
+	"github.com/ucan-wg/go-ucan/pkg/command"
+	"github.com/ucan-wg/go-ucan/pkg/policy"
+	"github.com/ucan-wg/go-ucan/pkg/policy/policytest"
+	"github.com/ucan-wg/go-ucan/token/delegation"
+	"github.com/ucan-wg/go-ucan/token/delegation/delegationtest"
+)
+
+const (
+	tokenNamePrefix      = "Token"
+	proorChainNamePrefix = "Proof"
+	tokenExt             = ".dagcbor"
+)
+
+var constantNonce = []byte{0x00, 0x01, 0x02, 0x03, 0x04, 0x05, 0x06, 0x07, 0x08, 0x09, 0x0a, 0x0b}
+
+type newDelegationParams struct {
+	privKey crypto.PrivKey // iss
+	aud     did.DID
+	cmd     command.Command
+	pol     policy.Policy
+	sub     did.DID
+	opts    []delegation.Option
+}
+
+type token struct {
+	name string
+	id   cid.Cid
+}
+
+type proof struct {
+	name string
+	prf  []cid.Cid
+}
+
+type acc struct {
+	name  string
+	chain []cid.Cid
+}
+
+type variant struct {
+	name    string
+	variant func(*newDelegationParams)
+}
+
+func noopVariant() variant {
+	return variant{
+		name:    "",
+		variant: func(_ *newDelegationParams) {},
+	}
+}
+
+type generator struct {
+	dlgs   []token
+	chains []proof
+}
+
+func (g *generator) chainPersonas(personas []didtest.Persona, acc acc, vari variant) error {
+	acc.name += personas[0].Name()
+
+	proofName := acc.name
+	if len(vari.name) > 0 {
+		proofName += "_" + vari.name
+	}
+	g.createProofChain(proofName, acc.chain)
+
+	if len(personas) < 2 {
+		return nil
+	}
+
+	name := personas[0].Name() + personas[1].Name()
+
+	params := newDelegationParams{
+		privKey: personas[0].PrivKey(),
+		aud:     personas[1].DID(),
+		cmd:     delegationtest.NominalCommand,
+		pol:     policytest.EmptyPolicy,
+		sub:     didtest.PersonaAlice.DID(),
+		opts: []delegation.Option{
+			delegation.WithNonce(constantNonce),
+		},
+	}
+
+	// Create each nominal token and continue the chain
+	id, err := g.createDelegation(params, name, vari)
+	if err != nil {
+		return err
+	}
+	acc.chain = append(acc.chain, id)
+	err = g.chainPersonas(personas[1:], acc, vari)
+	if err != nil {
+		return err
+	}
+
+	// If the user is Carol, create variants for each invalid and/or optional
+	// parameter and also continue the chain
+	if personas[0] == didtest.PersonaCarol {
+		variants := []variant{
+			{name: "InvalidExpandedCommand", variant: func(p *newDelegationParams) {
+				p.cmd = delegationtest.ExpandedCommand
+			}},
+			{name: "ValidAttenuatedCommand", variant: func(p *newDelegationParams) {
+				p.cmd = delegationtest.AttenuatedCommand
+			}},
+			{name: "InvalidSubject", variant: func(p *newDelegationParams) {
+				p.sub = didtest.PersonaBob.DID()
+			}},
+			{name: "InvalidExpired", variant: func(p *newDelegationParams) {
+				// Note: this makes the generator not deterministic
+				p.opts = append(p.opts, delegation.WithExpiration(time.Now().Add(time.Second)))
+			}},
+			{name: "InvalidInactive", variant: func(p *newDelegationParams) {
+				nbf, err := time.Parse(time.RFC3339, "2070-01-01T00:00:00Z")
+				if err != nil {
+					panic(err)
+				}
+				p.opts = append(p.opts, delegation.WithNotBefore(nbf))
+			}},
+			{name: "ValidExamplePolicy", variant: func(p *newDelegationParams) {
+				p.pol = policytest.SpecPolicy
+			}},
+		}
+
+		// Start a branch in the recursion for each of the variants
+		for _, v := range variants {
+			id, err := g.createDelegation(params, name, v)
+			if err != nil {
+				return err
+			}
+
+			// replace the previous Carol token id with the one from the variant
+			acc.chain[len(acc.chain)-1] = id
+			err = g.chainPersonas(personas[1:], acc, v)
+			if err != nil {
+				return err
+			}
+		}
+	}
+	return nil
+}
+
+func (g *generator) createDelegation(params newDelegationParams, name string, vari variant) (cid.Cid, error) {
+	vari.variant(&params)
+
+	issDID, err := did.FromPrivKey(params.privKey)
+	if err != nil {
+		return cid.Undef, err
+	}
+
+	tkn, err := delegation.New(issDID, params.aud, params.cmd, params.pol, params.sub, params.opts...)
+	if err != nil {
+		return cid.Undef, err
+	}
+
+	data, id, err := tkn.ToSealed(params.privKey)
+	if err != nil {
+		return cid.Undef, err
+	}
+
+	dlgName := tokenNamePrefix + name
+	if len(vari.name) > 0 {
+		dlgName += "_" + vari.name
+	}
+
+	err = os.WriteFile(filepath.Join("..", delegationtest.TokenDir, dlgName+tokenExt), data, 0o644)
+	if err != nil {
+		return cid.Undef, err
+	}
+
+	g.dlgs = append(g.dlgs, token{
+		name: dlgName,
+		id:   id,
+	})
+
+	return id, nil
+}
+
+func (g *generator) createProofChain(name string, prf []cid.Cid) {
+	if len(prf) < 1 {
+		return
+	}
+
+	clone := make([]cid.Cid, len(prf))
+	copy(clone, prf)
+
+	g.chains = append(g.chains, proof{
+		name: proorChainNamePrefix + name,
+		prf:  clone,
+	})
+}
+
+func (g *generator) writeGoFile() error {
+	buf := bytes.NewBuffer(nil)
+
+	Println := func(a ...any) { _, _ = fmt.Fprintln(buf, a...) }
+	Printf := func(format string, a ...any) { _, _ = fmt.Fprintf(buf, format, a...) }
+
+	Println("// Code generated by delegationtest - DO NOT EDIT.")
+	Println()
+	Println("package delegationtest")
+	Println()
+	Println("import (")
+	Println("\t\"github.com/ipfs/go-cid\"")
+	Println()
+	Println("\t\"github.com/ucan-wg/go-ucan/token/delegation\"")
+	Println(")")
+
+	refs := make(map[cid.Cid]string, len(g.dlgs))
+
+	for _, d := range g.dlgs {
+		refs[d.id] = d.name + "CID"
+
+		Println()
+		Println("var (")
+		Printf("\t%sCID    = cid.MustParse(\"%s\")\n", d.name, d.id.String())
+		Printf("\t%sSealed = mustGetBundle(%s).Sealed\n", d.name, d.name+"CID")
+		Printf("\t%sBundle = mustGetBundle(%s)\n", d.name, d.name+"CID")
+		Printf("\t%s       = mustGetBundle(%s).Decoded\n", d.name, d.name+"CID")
+		Println(")")
+	}
+
+	Println()
+	Println("var AllTokens = []*delegation.Token{")
+	for _, d := range g.dlgs {
+		Printf("\t%s,\n", d.name)
+	}
+	Println("}")
+
+	Println()
+	Println("var AllBundles = []delegation.Bundle{")
+	for _, d := range g.dlgs {
+		Printf("\t%sBundle,\n", d.name)
+	}
+	Println("}")
+
+	Println()
+	Println("var cidToName = map[cid.Cid]string{")
+	for _, d := range g.dlgs {
+		Printf("\t%sCID: \"%s\",\n", d.name, d.name)
+	}
+	Println("}")
+
+	for _, c := range g.chains {
+		Println()
+		Printf("var %s = []cid.Cid{\n", c.name)
+
+		for _, d := range slices.Backward(c.prf) {
+			Printf("\t%s,\n", refs[d])
+		}
+
+		Println("}")
+	}
+
+	out, err := format.Source(buf.Bytes())
+	if err != nil {
+		return err
+	}
+
+	return os.WriteFile("../token_gen.go", out, 0666)
+}

token/delegation/delegationtest/generator/main.go

@@ -0,0 +1,17 @@
+package main
+
+import (
+	"github.com/ucan-wg/go-ucan/did/didtest"
+)
+
+func main() {
+	gen := &generator{}
+	err := gen.chainPersonas(didtest.Personas(), acc{}, noopVariant())
+	if err != nil {
+		panic(err)
+	}
+	err = gen.writeGoFile()
+	if err != nil {
+		panic(err)
+	}
+}

token/delegation/delegationtest/token.go

@@ -0,0 +1,115 @@
+package delegationtest
+
+import (
+	"embed"
+	"path/filepath"
+	"sync"
+
+	"github.com/ipfs/go-cid"
+
+	"github.com/ucan-wg/go-ucan/pkg/command"
+	"github.com/ucan-wg/go-ucan/token/delegation"
+)
+
+var (
+	// ExpandedCommand is the parent of the NominalCommand and represents
+	// the cases where the delegation proof-chain or invocation token tries
+	// to increase the privileges granted by the root delegation token.
+	// Execution of this command is generally prohibited in tests.
+	ExpandedCommand = command.MustParse("/expanded")
+
+	// NominalCommand is the command used for most test tokens and proof-chains.
+	// Execution of this command is generally allowed in tests.
+	NominalCommand = ExpandedCommand.Join("nominal")
+
+	// AttenuatedCommand is a sub-command of the NominalCommand.
+	// Execution of this command is generally allowed in tests.
+	AttenuatedCommand = NominalCommand.Join("attenuated")
+)
+
+// ProofEmpty provides an empty proof chain for testing purposes.
+var ProofEmpty = []cid.Cid{}
+
+const TokenDir = "data"
+
+//go:embed data
+var fs embed.FS
+
+var _ delegation.Loader = (*DelegationLoader)(nil)
+
+type DelegationLoader struct {
+	bundles map[cid.Cid]delegation.Bundle
+}
+
+var (
+	once sync.Once
+	ldr  *DelegationLoader
+)
+
+// GetDelegationLoader returns a singleton instance of a test
+// DelegationLoader containing all the tokens present in the data/
+// directory.
+func GetDelegationLoader() *DelegationLoader {
+	once.Do(func() {
+		var err error
+		ldr, err = loadDelegations()
+		if err != nil {
+			panic(err)
+		}
+	})
+	return ldr
+}
+
+// GetDelegation implements invocation.DelegationLoader.
+func (l *DelegationLoader) GetDelegation(id cid.Cid) (*delegation.Token, error) {
+	bundle, ok := l.bundles[id]
+	if !ok {
+		return nil, delegation.ErrDelegationNotFound
+	}
+	return bundle.Decoded, nil
+}
+
+func loadDelegations() (*DelegationLoader, error) {
+	dirEntries, err := fs.ReadDir(TokenDir)
+	if err != nil {
+		return nil, err
+	}
+
+	bundles := make(map[cid.Cid]delegation.Bundle, len(dirEntries))
+
+	for _, dirEntry := range dirEntries {
+		data, err := fs.ReadFile(filepath.Join(TokenDir, dirEntry.Name()))
+		if err != nil {
+			return nil, err
+		}
+
+		tkn, id, err := delegation.FromSealed(data)
+		if err != nil {
+			return nil, err
+		}
+
+		bundles[id] = delegation.Bundle{Cid: id, Decoded: tkn, Sealed: data}
+	}
+
+	return &DelegationLoader{
+		bundles: bundles,
+	}, nil
+}
+
+// GetDelegation is a shortcut that gets (or creates) the DelegationLoader
+// and attempts to return the token referenced by the provided CID.
+func GetDelegation(id cid.Cid) (*delegation.Token, error) {
+	return GetDelegationLoader().GetDelegation(id)
+}
+
+func CidToName(id cid.Cid) string {
+	return cidToName[id]
+}
+
+func mustGetBundle(id cid.Cid) delegation.Bundle {
+	bundle, ok := GetDelegationLoader().bundles[id]
+	if !ok {
+		panic(delegation.ErrDelegationNotFound)
+	}
+	return bundle
+}

token/delegation/delegationtest/token_gen.go

@@ -0,0 +1,404 @@
+// Code generated by delegationtest - DO NOT EDIT.
+
+package delegationtest
+
+import (
+	"github.com/ipfs/go-cid"
+
+	"github.com/ucan-wg/go-ucan/token/delegation"
+)
+
+var (
+	TokenAliceBobCID    = cid.MustParse("bafyreicidrwvmac5lvjypucgityrtjsknojraio7ujjli4r5eyby66wjzm")
+	TokenAliceBobSealed = mustGetBundle(TokenAliceBobCID).Sealed
+	TokenAliceBobBundle = mustGetBundle(TokenAliceBobCID)
+	TokenAliceBob       = mustGetBundle(TokenAliceBobCID).Decoded
+)
+
+var (
+	TokenBobCarolCID    = cid.MustParse("bafyreihxv2uhq43oxllzs2xfvxst7wtvvvl7pohb2chcz6hjvfv2ntea5u")
+	TokenBobCarolSealed = mustGetBundle(TokenBobCarolCID).Sealed
+	TokenBobCarolBundle = mustGetBundle(TokenBobCarolCID)
+	TokenBobCarol       = mustGetBundle(TokenBobCarolCID).Decoded
+)
+
+var (
+	TokenCarolDanCID    = cid.MustParse("bafyreihclsgiroazq3heqdswvj2cafwqbpboicq7immo65scl7ahktpsdq")
+	TokenCarolDanSealed = mustGetBundle(TokenCarolDanCID).Sealed
+	TokenCarolDanBundle = mustGetBundle(TokenCarolDanCID)
+	TokenCarolDan       = mustGetBundle(TokenCarolDanCID).Decoded
+)
+
+var (
+	TokenDanErinCID    = cid.MustParse("bafyreicja6ihewy64p3ake56xukotafjlkh4uqep2qhj52en46zzfwby3e")
+	TokenDanErinSealed = mustGetBundle(TokenDanErinCID).Sealed
+	TokenDanErinBundle = mustGetBundle(TokenDanErinCID)
+	TokenDanErin       = mustGetBundle(TokenDanErinCID).Decoded
+)
+
+var (
+	TokenErinFrankCID    = cid.MustParse("bafyreicjlx3lobxm6hl5s4htd4ydwkkqeiou6rft4rnvulfdyoew565vka")
+	TokenErinFrankSealed = mustGetBundle(TokenErinFrankCID).Sealed
+	TokenErinFrankBundle = mustGetBundle(TokenErinFrankCID)
+	TokenErinFrank       = mustGetBundle(TokenErinFrankCID).Decoded
+)
+
+var (
+	TokenCarolDan_InvalidExpandedCommandCID    = cid.MustParse("bafyreid3m3pk53gqgp5rlzqhvpedbwsqbidqlp4yz64vknwbzj7bxrmsr4")
+	TokenCarolDan_InvalidExpandedCommandSealed = mustGetBundle(TokenCarolDan_InvalidExpandedCommandCID).Sealed
+	TokenCarolDan_InvalidExpandedCommandBundle = mustGetBundle(TokenCarolDan_InvalidExpandedCommandCID)
+	TokenCarolDan_InvalidExpandedCommand       = mustGetBundle(TokenCarolDan_InvalidExpandedCommandCID).Decoded
+)
+
+var (
+	TokenDanErin_InvalidExpandedCommandCID    = cid.MustParse("bafyreifn4sy5onwajx3kqvot5mib6m6xarzrqjozqbzgmzpmc5ox3g2uzm")
+	TokenDanErin_InvalidExpandedCommandSealed = mustGetBundle(TokenDanErin_InvalidExpandedCommandCID).Sealed
+	TokenDanErin_InvalidExpandedCommandBundle = mustGetBundle(TokenDanErin_InvalidExpandedCommandCID)
+	TokenDanErin_InvalidExpandedCommand       = mustGetBundle(TokenDanErin_InvalidExpandedCommandCID).Decoded
+)
+
+var (
+	TokenErinFrank_InvalidExpandedCommandCID    = cid.MustParse("bafyreidmpgd36jznmq42bs34o4qi3fcbrsh4idkg6ejahudejzwb76fwxe")
+	TokenErinFrank_InvalidExpandedCommandSealed = mustGetBundle(TokenErinFrank_InvalidExpandedCommandCID).Sealed
+	TokenErinFrank_InvalidExpandedCommandBundle = mustGetBundle(TokenErinFrank_InvalidExpandedCommandCID)
+	TokenErinFrank_InvalidExpandedCommand       = mustGetBundle(TokenErinFrank_InvalidExpandedCommandCID).Decoded
+)
+
+var (
+	TokenCarolDan_ValidAttenuatedCommandCID    = cid.MustParse("bafyreiekhtm237vyapk3c6voeb5lnz54crebqdqi3x4wn4u4cbrrhzsqfe")
+	TokenCarolDan_ValidAttenuatedCommandSealed = mustGetBundle(TokenCarolDan_ValidAttenuatedCommandCID).Sealed
+	TokenCarolDan_ValidAttenuatedCommandBundle = mustGetBundle(TokenCarolDan_ValidAttenuatedCommandCID)
+	TokenCarolDan_ValidAttenuatedCommand       = mustGetBundle(TokenCarolDan_ValidAttenuatedCommandCID).Decoded
+)
+
+var (
+	TokenDanErin_ValidAttenuatedCommandCID    = cid.MustParse("bafyreicrvzqferyy7rgo75l5rn6r2nl7zyeexxjmu3dm4ff7rn2coblj4y")
+	TokenDanErin_ValidAttenuatedCommandSealed = mustGetBundle(TokenDanErin_ValidAttenuatedCommandCID).Sealed
+	TokenDanErin_ValidAttenuatedCommandBundle = mustGetBundle(TokenDanErin_ValidAttenuatedCommandCID)
+	TokenDanErin_ValidAttenuatedCommand       = mustGetBundle(TokenDanErin_ValidAttenuatedCommandCID).Decoded
+)
+
+var (
+	TokenErinFrank_ValidAttenuatedCommandCID    = cid.MustParse("bafyreie6fhspk53kplcc2phla3e7z7fzldlbmmpuwk6nbow5q6s2zjmw2q")
+	TokenErinFrank_ValidAttenuatedCommandSealed = mustGetBundle(TokenErinFrank_ValidAttenuatedCommandCID).Sealed
+	TokenErinFrank_ValidAttenuatedCommandBundle = mustGetBundle(TokenErinFrank_ValidAttenuatedCommandCID)
+	TokenErinFrank_ValidAttenuatedCommand       = mustGetBundle(TokenErinFrank_ValidAttenuatedCommandCID).Decoded
+)
+
+var (
+	TokenCarolDan_InvalidSubjectCID    = cid.MustParse("bafyreifgksz6756if42tnc6rqsnbaa2u3fdrveo7ek44lnj2d64d5sw26u")
+	TokenCarolDan_InvalidSubjectSealed = mustGetBundle(TokenCarolDan_InvalidSubjectCID).Sealed
+	TokenCarolDan_InvalidSubjectBundle = mustGetBundle(TokenCarolDan_InvalidSubjectCID)
+	TokenCarolDan_InvalidSubject       = mustGetBundle(TokenCarolDan_InvalidSubjectCID).Decoded
+)
+
+var (
+	TokenDanErin_InvalidSubjectCID    = cid.MustParse("bafyreibdwew5nypsxrm4fq73wu6hw3lgwwiolj3bi33xdrbgcf3ogm6fty")
+	TokenDanErin_InvalidSubjectSealed = mustGetBundle(TokenDanErin_InvalidSubjectCID).Sealed
+	TokenDanErin_InvalidSubjectBundle = mustGetBundle(TokenDanErin_InvalidSubjectCID)
+	TokenDanErin_InvalidSubject       = mustGetBundle(TokenDanErin_InvalidSubjectCID).Decoded
+)
+
+var (
+	TokenErinFrank_InvalidSubjectCID    = cid.MustParse("bafyreicr364mj3n7x4iyhcksxypelktcqkkw3ptg7ggxtqegw3p3mr6zc4")
+	TokenErinFrank_InvalidSubjectSealed = mustGetBundle(TokenErinFrank_InvalidSubjectCID).Sealed
+	TokenErinFrank_InvalidSubjectBundle = mustGetBundle(TokenErinFrank_InvalidSubjectCID)
+	TokenErinFrank_InvalidSubject       = mustGetBundle(TokenErinFrank_InvalidSubjectCID).Decoded
+)
+
+var (
+	TokenCarolDan_InvalidExpiredCID    = cid.MustParse("bafyreifyzm5jkx2sfu5awyndg3dn5zlg7sq5hssgfatafk62kiiilapnqe")
+	TokenCarolDan_InvalidExpiredSealed = mustGetBundle(TokenCarolDan_InvalidExpiredCID).Sealed
+	TokenCarolDan_InvalidExpiredBundle = mustGetBundle(TokenCarolDan_InvalidExpiredCID)
+	TokenCarolDan_InvalidExpired       = mustGetBundle(TokenCarolDan_InvalidExpiredCID).Decoded
+)
+
+var (
+	TokenDanErin_InvalidExpiredCID    = cid.MustParse("bafyreihhnisabmkofuk3qaw37leijxqjaz5or6v2cufjxwzdkvuvv2dzbq")
+	TokenDanErin_InvalidExpiredSealed = mustGetBundle(TokenDanErin_InvalidExpiredCID).Sealed
+	TokenDanErin_InvalidExpiredBundle = mustGetBundle(TokenDanErin_InvalidExpiredCID)
+	TokenDanErin_InvalidExpired       = mustGetBundle(TokenDanErin_InvalidExpiredCID).Decoded
+)
+
+var (
+	TokenErinFrank_InvalidExpiredCID    = cid.MustParse("bafyreigeokaziviwm5kzmkpwesj3gta5k7zrd62x4a746fnrnkhvatwbna")
+	TokenErinFrank_InvalidExpiredSealed = mustGetBundle(TokenErinFrank_InvalidExpiredCID).Sealed
+	TokenErinFrank_InvalidExpiredBundle = mustGetBundle(TokenErinFrank_InvalidExpiredCID)
+	TokenErinFrank_InvalidExpired       = mustGetBundle(TokenErinFrank_InvalidExpiredCID).Decoded
+)
+
+var (
+	TokenCarolDan_InvalidInactiveCID    = cid.MustParse("bafyreicea5y2nvlitvxijkupeavtg23i7ktjk3uejnaquguurzptiabk4u")
+	TokenCarolDan_InvalidInactiveSealed = mustGetBundle(TokenCarolDan_InvalidInactiveCID).Sealed
+	TokenCarolDan_InvalidInactiveBundle = mustGetBundle(TokenCarolDan_InvalidInactiveCID)
+	TokenCarolDan_InvalidInactive       = mustGetBundle(TokenCarolDan_InvalidInactiveCID).Decoded
+)
+
+var (
+	TokenDanErin_InvalidInactiveCID    = cid.MustParse("bafyreifsgqzkmxj2vexuts3z766mwcjreiisjg2jykyzf7tbj5sclutpvq")
+	TokenDanErin_InvalidInactiveSealed = mustGetBundle(TokenDanErin_InvalidInactiveCID).Sealed
+	TokenDanErin_InvalidInactiveBundle = mustGetBundle(TokenDanErin_InvalidInactiveCID)
+	TokenDanErin_InvalidInactive       = mustGetBundle(TokenDanErin_InvalidInactiveCID).Decoded
+)
+
+var (
+	TokenErinFrank_InvalidInactiveCID    = cid.MustParse("bafyreifbfegon24c6dndiqyktahzs65vhyasrygbw7nhsvojn6distsdre")
+	TokenErinFrank_InvalidInactiveSealed = mustGetBundle(TokenErinFrank_InvalidInactiveCID).Sealed
+	TokenErinFrank_InvalidInactiveBundle = mustGetBundle(TokenErinFrank_InvalidInactiveCID)
+	TokenErinFrank_InvalidInactive       = mustGetBundle(TokenErinFrank_InvalidInactiveCID).Decoded
+)
+
+var (
+	TokenCarolDan_ValidExamplePolicyCID    = cid.MustParse("bafyreibtfrp2njnkjrcuhxd4ebaecmpcql5knek2h2j2fjzu2sij2tv6ei")
+	TokenCarolDan_ValidExamplePolicySealed = mustGetBundle(TokenCarolDan_ValidExamplePolicyCID).Sealed
+	TokenCarolDan_ValidExamplePolicyBundle = mustGetBundle(TokenCarolDan_ValidExamplePolicyCID)
+	TokenCarolDan_ValidExamplePolicy       = mustGetBundle(TokenCarolDan_ValidExamplePolicyCID).Decoded
+)
+
+var (
+	TokenDanErin_ValidExamplePolicyCID    = cid.MustParse("bafyreidxfwbkzujpu7ivulkc7b6ff4cpbzrkeklmxqvyhhmkmym5b45e2e")
+	TokenDanErin_ValidExamplePolicySealed = mustGetBundle(TokenDanErin_ValidExamplePolicyCID).Sealed
+	TokenDanErin_ValidExamplePolicyBundle = mustGetBundle(TokenDanErin_ValidExamplePolicyCID)
+	TokenDanErin_ValidExamplePolicy       = mustGetBundle(TokenDanErin_ValidExamplePolicyCID).Decoded
+)
+
+var (
+	TokenErinFrank_ValidExamplePolicyCID    = cid.MustParse("bafyreiatkvtvgakqcrdk6vgrv7tbq5rbeiqct52ep4plcftp2agffjyvp4")
+	TokenErinFrank_ValidExamplePolicySealed = mustGetBundle(TokenErinFrank_ValidExamplePolicyCID).Sealed
+	TokenErinFrank_ValidExamplePolicyBundle = mustGetBundle(TokenErinFrank_ValidExamplePolicyCID)
+	TokenErinFrank_ValidExamplePolicy       = mustGetBundle(TokenErinFrank_ValidExamplePolicyCID).Decoded
+)
+
+var AllTokens = []*delegation.Token{
+	TokenAliceBob,
+	TokenBobCarol,
+	TokenCarolDan,
+	TokenDanErin,
+	TokenErinFrank,
+	TokenCarolDan_InvalidExpandedCommand,
+	TokenDanErin_InvalidExpandedCommand,
+	TokenErinFrank_InvalidExpandedCommand,
+	TokenCarolDan_ValidAttenuatedCommand,
+	TokenDanErin_ValidAttenuatedCommand,
+	TokenErinFrank_ValidAttenuatedCommand,
+	TokenCarolDan_InvalidSubject,
+	TokenDanErin_InvalidSubject,
+	TokenErinFrank_InvalidSubject,
+	TokenCarolDan_InvalidExpired,
+	TokenDanErin_InvalidExpired,
+	TokenErinFrank_InvalidExpired,
+	TokenCarolDan_InvalidInactive,
+	TokenDanErin_InvalidInactive,
+	TokenErinFrank_InvalidInactive,
+	TokenCarolDan_ValidExamplePolicy,
+	TokenDanErin_ValidExamplePolicy,
+	TokenErinFrank_ValidExamplePolicy,
+}
+
+var AllBundles = []delegation.Bundle{
+	TokenAliceBobBundle,
+	TokenBobCarolBundle,
+	TokenCarolDanBundle,
+	TokenDanErinBundle,
+	TokenErinFrankBundle,
+	TokenCarolDan_InvalidExpandedCommandBundle,
+	TokenDanErin_InvalidExpandedCommandBundle,
+	TokenErinFrank_InvalidExpandedCommandBundle,
+	TokenCarolDan_ValidAttenuatedCommandBundle,
+	TokenDanErin_ValidAttenuatedCommandBundle,
+	TokenErinFrank_ValidAttenuatedCommandBundle,
+	TokenCarolDan_InvalidSubjectBundle,
+	TokenDanErin_InvalidSubjectBundle,
+	TokenErinFrank_InvalidSubjectBundle,
+	TokenCarolDan_InvalidExpiredBundle,
+	TokenDanErin_InvalidExpiredBundle,
+	TokenErinFrank_InvalidExpiredBundle,
+	TokenCarolDan_InvalidInactiveBundle,
+	TokenDanErin_InvalidInactiveBundle,
+	TokenErinFrank_InvalidInactiveBundle,
+	TokenCarolDan_ValidExamplePolicyBundle,
+	TokenDanErin_ValidExamplePolicyBundle,
+	TokenErinFrank_ValidExamplePolicyBundle,
+}
+
+var cidToName = map[cid.Cid]string{
+	TokenAliceBobCID:                         "TokenAliceBob",
+	TokenBobCarolCID:                         "TokenBobCarol",
+	TokenCarolDanCID:                         "TokenCarolDan",
+	TokenDanErinCID:                          "TokenDanErin",
+	TokenErinFrankCID:                        "TokenErinFrank",
+	TokenCarolDan_InvalidExpandedCommandCID:  "TokenCarolDan_InvalidExpandedCommand",
+	TokenDanErin_InvalidExpandedCommandCID:   "TokenDanErin_InvalidExpandedCommand",
+	TokenErinFrank_InvalidExpandedCommandCID: "TokenErinFrank_InvalidExpandedCommand",
+	TokenCarolDan_ValidAttenuatedCommandCID:  "TokenCarolDan_ValidAttenuatedCommand",
+	TokenDanErin_ValidAttenuatedCommandCID:   "TokenDanErin_ValidAttenuatedCommand",
+	TokenErinFrank_ValidAttenuatedCommandCID: "TokenErinFrank_ValidAttenuatedCommand",
+	TokenCarolDan_InvalidSubjectCID:          "TokenCarolDan_InvalidSubject",
+	TokenDanErin_InvalidSubjectCID:           "TokenDanErin_InvalidSubject",
+	TokenErinFrank_InvalidSubjectCID:         "TokenErinFrank_InvalidSubject",
+	TokenCarolDan_InvalidExpiredCID:          "TokenCarolDan_InvalidExpired",
+	TokenDanErin_InvalidExpiredCID:           "TokenDanErin_InvalidExpired",
+	TokenErinFrank_InvalidExpiredCID:         "TokenErinFrank_InvalidExpired",
+	TokenCarolDan_InvalidInactiveCID:         "TokenCarolDan_InvalidInactive",
+	TokenDanErin_InvalidInactiveCID:          "TokenDanErin_InvalidInactive",
+	TokenErinFrank_InvalidInactiveCID:        "TokenErinFrank_InvalidInactive",
+	TokenCarolDan_ValidExamplePolicyCID:      "TokenCarolDan_ValidExamplePolicy",
+	TokenDanErin_ValidExamplePolicyCID:       "TokenDanErin_ValidExamplePolicy",
+	TokenErinFrank_ValidExamplePolicyCID:     "TokenErinFrank_ValidExamplePolicy",
+}
+
+var ProofAliceBob = []cid.Cid{
+	TokenAliceBobCID,
+}
+
+var ProofAliceBobCarol = []cid.Cid{
+	TokenBobCarolCID,
+	TokenAliceBobCID,
+}
+
+var ProofAliceBobCarolDan = []cid.Cid{
+	TokenCarolDanCID,
+	TokenBobCarolCID,
+	TokenAliceBobCID,
+}
+
+var ProofAliceBobCarolDanErin = []cid.Cid{
+	TokenDanErinCID,
+	TokenCarolDanCID,
+	TokenBobCarolCID,
+	TokenAliceBobCID,
+}
+
+var ProofAliceBobCarolDanErinFrank = []cid.Cid{
+	TokenErinFrankCID,
+	TokenDanErinCID,
+	TokenCarolDanCID,
+	TokenBobCarolCID,
+	TokenAliceBobCID,
+}
+
+var ProofAliceBobCarolDan_InvalidExpandedCommand = []cid.Cid{
+	TokenCarolDan_InvalidExpandedCommandCID,
+	TokenBobCarolCID,
+	TokenAliceBobCID,
+}
+
+var ProofAliceBobCarolDanErin_InvalidExpandedCommand = []cid.Cid{
+	TokenDanErin_InvalidExpandedCommandCID,
+	TokenCarolDan_InvalidExpandedCommandCID,
+	TokenBobCarolCID,
+	TokenAliceBobCID,
+}
+
+var ProofAliceBobCarolDanErinFrank_InvalidExpandedCommand = []cid.Cid{
+	TokenErinFrank_InvalidExpandedCommandCID,
+	TokenDanErin_InvalidExpandedCommandCID,
+	TokenCarolDan_InvalidExpandedCommandCID,
+	TokenBobCarolCID,
+	TokenAliceBobCID,
+}
+
+var ProofAliceBobCarolDan_ValidAttenuatedCommand = []cid.Cid{
+	TokenCarolDan_ValidAttenuatedCommandCID,
+	TokenBobCarolCID,
+	TokenAliceBobCID,
+}
+
+var ProofAliceBobCarolDanErin_ValidAttenuatedCommand = []cid.Cid{
+	TokenDanErin_ValidAttenuatedCommandCID,
+	TokenCarolDan_ValidAttenuatedCommandCID,
+	TokenBobCarolCID,
+	TokenAliceBobCID,
+}
+
+var ProofAliceBobCarolDanErinFrank_ValidAttenuatedCommand = []cid.Cid{
+	TokenErinFrank_ValidAttenuatedCommandCID,
+	TokenDanErin_ValidAttenuatedCommandCID,
+	TokenCarolDan_ValidAttenuatedCommandCID,
+	TokenBobCarolCID,
+	TokenAliceBobCID,
+}
+
+var ProofAliceBobCarolDan_InvalidSubject = []cid.Cid{
+	TokenCarolDan_InvalidSubjectCID,
+	TokenBobCarolCID,
+	TokenAliceBobCID,
+}
+
+var ProofAliceBobCarolDanErin_InvalidSubject = []cid.Cid{
+	TokenDanErin_InvalidSubjectCID,
+	TokenCarolDan_InvalidSubjectCID,
+	TokenBobCarolCID,
+	TokenAliceBobCID,
+}
+
+var ProofAliceBobCarolDanErinFrank_InvalidSubject = []cid.Cid{
+	TokenErinFrank_InvalidSubjectCID,
+	TokenDanErin_InvalidSubjectCID,
+	TokenCarolDan_InvalidSubjectCID,
+	TokenBobCarolCID,
+	TokenAliceBobCID,
+}
+
+var ProofAliceBobCarolDan_InvalidExpired = []cid.Cid{
+	TokenCarolDan_InvalidExpiredCID,
+	TokenBobCarolCID,
+	TokenAliceBobCID,
+}
+
+var ProofAliceBobCarolDanErin_InvalidExpired = []cid.Cid{
+	TokenDanErin_InvalidExpiredCID,
+	TokenCarolDan_InvalidExpiredCID,
+	TokenBobCarolCID,
+	TokenAliceBobCID,
+}
+
+var ProofAliceBobCarolDanErinFrank_InvalidExpired = []cid.Cid{
+	TokenErinFrank_InvalidExpiredCID,
+	TokenDanErin_InvalidExpiredCID,
+	TokenCarolDan_InvalidExpiredCID,
+	TokenBobCarolCID,
+	TokenAliceBobCID,
+}
+
+var ProofAliceBobCarolDan_InvalidInactive = []cid.Cid{
+	TokenCarolDan_InvalidInactiveCID,
+	TokenBobCarolCID,
+	TokenAliceBobCID,
+}
+
+var ProofAliceBobCarolDanErin_InvalidInactive = []cid.Cid{
+	TokenDanErin_InvalidInactiveCID,
+	TokenCarolDan_InvalidInactiveCID,
+	TokenBobCarolCID,
+	TokenAliceBobCID,
+}
+
+var ProofAliceBobCarolDanErinFrank_InvalidInactive = []cid.Cid{
+	TokenErinFrank_InvalidInactiveCID,
+	TokenDanErin_InvalidInactiveCID,
+	TokenCarolDan_InvalidInactiveCID,
+	TokenBobCarolCID,
+	TokenAliceBobCID,
+}
+
+var ProofAliceBobCarolDan_ValidExamplePolicy = []cid.Cid{
+	TokenCarolDan_ValidExamplePolicyCID,
+	TokenBobCarolCID,
+	TokenAliceBobCID,
+}
+
+var ProofAliceBobCarolDanErin_ValidExamplePolicy = []cid.Cid{
+	TokenDanErin_ValidExamplePolicyCID,
+	TokenCarolDan_ValidExamplePolicyCID,
+	TokenBobCarolCID,
+	TokenAliceBobCID,
+}
+
+var ProofAliceBobCarolDanErinFrank_ValidExamplePolicy = []cid.Cid{
+	TokenErinFrank_ValidExamplePolicyCID,
+	TokenDanErin_ValidExamplePolicyCID,
+	TokenCarolDan_ValidExamplePolicyCID,
+	TokenBobCarolCID,
+	TokenAliceBobCID,
+}

token/delegation/delegationtest/token_test.go

@@ -0,0 +1,30 @@
+package delegationtest_test
+
+import (
+	"testing"
+
+	"github.com/ipfs/go-cid"
+	"github.com/stretchr/testify/assert"
+	"github.com/stretchr/testify/require"
+
+	"github.com/ucan-wg/go-ucan/token/delegation"
+	"github.com/ucan-wg/go-ucan/token/delegation/delegationtest"
+)
+
+func TestGetDelegation(t *testing.T) {
+	t.Run("passes with valid CID", func(t *testing.T) {
+		t.Parallel()
+
+		tkn, err := delegationtest.GetDelegation(delegationtest.TokenAliceBobCID)
+		require.NoError(t, err)
+		assert.NotZero(t, tkn)
+	})
+
+	t.Run("fails with unknown CID", func(t *testing.T) {
+		t.Parallel()
+
+		tkn, err := delegationtest.GetDelegation(cid.Undef)
+		require.ErrorIs(t, err, delegation.ErrDelegationNotFound)
+		assert.Nil(t, tkn)
+	})
+}

token/delegation/examples_test.go

@@ -2,7 +2,6 @@ package delegation_test
 
 import (
 	"bytes"
-	"crypto/rand"
 	"encoding/base64"
 	"encoding/hex"
 	"encoding/json"
@@ -13,9 +12,8 @@ import (
 	"github.com/ipld/go-ipld-prime"
 	"github.com/ipld/go-ipld-prime/codec/dagcbor"
 	"github.com/ipld/go-ipld-prime/codec/dagjson"
-	"github.com/libp2p/go-libp2p/core/crypto"
 
-	"github.com/ucan-wg/go-ucan/did"
+	"github.com/ucan-wg/go-ucan/did/didtest"
 	"github.com/ucan-wg/go-ucan/pkg/command"
 	"github.com/ucan-wg/go-ucan/pkg/policy"
 	"github.com/ucan-wg/go-ucan/pkg/policy/literal"
@@ -26,15 +24,7 @@ import (
 // The following example shows how to create a delegation.Token with
 // distinct DIDs for issuer (iss), audience (aud) and subject (sub).
 func ExampleNew() {
-	issPriv, issPub, err := crypto.GenerateEd25519Key(rand.Reader)
-	printThenPanicOnErr(err)
-
-	issDid, err := did.FromPubKey(issPub)
-	printThenPanicOnErr(err)
-	fmt.Println("issDid:", issDid)
-
-	audDid := did.MustParse(AudienceDID)
-	subDid := did.MustParse(subjectDID)
+	fmt.Println("issDid:", didtest.PersonaBob.DID().String())
 
 	// The command defines the shape of the arguments that will be evaluated against the policy
 	cmd := command.MustParse("/foo/bar")
@@ -51,8 +41,7 @@ func ExampleNew() {
 		)),
 	)
 
-	tkn, err := delegation.New(issPriv, audDid, cmd, pol,
-		delegation.WithSubject(subDid),
+	tkn, err := delegation.New(didtest.PersonaBob.DID(), didtest.PersonaCarol.DID(), cmd, pol, didtest.PersonaAlice.DID(),
 		delegation.WithExpirationIn(time.Hour),
 		delegation.WithNotBeforeIn(time.Minute),
 		delegation.WithMeta("foo", "bar"),
@@ -61,101 +50,91 @@ func ExampleNew() {
 	printThenPanicOnErr(err)
 
 	// "Seal", meaning encode and wrap into a signed envelope.
-	data, id, err := tkn.ToSealed(issPriv)
+	data, id, err := tkn.ToSealed(didtest.PersonaBob.PrivKey())
 	printThenPanicOnErr(err)
 
 	printCIDAndSealed(id, data)
 
 	// Example output:
 	//
-	// issDid: did:key:z6MkhVFznPeR572rTK51UjoTNpnF8cxuWfPm9oBMPr7y8ABe
+	// issDid: did:key:z6MkvJPmEZZYbgiw1ouT1oouTsTFBHJSts9ophVsNgcRmYxU
 	//
-	// CID (base58BTC): zdpuAv6g2eJSc4RJwEpmooGLVK4wJ4CZpnM92tPVYt5jtMoLW
-	//
-	// DAG-CBOR (base64) out: 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
+	// CID (base58BTC): zdpuAsqfZkgg2jgZyob23sq1J9xwtf9PHgt1PsskVCMq7Vvxk
 	//
+	// DAG-CBOR (base64) out: 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
 	// Converted to DAG-JSON out:
-	// [
-	//	{
-	//		"/": {
-	//			"bytes": "5rvl8uKmDVGvAVSt4m/0MGiXl9dZwljJJ9m2qHCoIB617l26UvMxyH5uvN9hM7ozfVATiq4mLhoGgm9IGnEEAg"
-	//		}
-	//	},
-	//	{
-	//		"h": {
+	//	[
+	//		{
 	//			"/": {
-	//				"bytes": "NO0BcQ"
+	//				"bytes": "5rvl8uKmDVGvAVSt4m/0MGiXl9dZwljJJ9m2qHCoIB617l26UvMxyH5uvN9hM7ozfVATiq4mLhoGgm9IGnEEAg"
 	//			}
 	//		},
-	//		"ucan/dlg@1.0.0-rc.1": {
-	//			"aud": "did:key:z6Mkq5YmbJcTrPExNDi26imrTCpKhepjBFBSHqrBDN2ArPkv",
-	//			"cmd": "/foo/bar",
-	//			"exp": 1728933098,
-	//			"iss": "did:key:z6MkhVFznPeR572rTK51UjoTNpnF8cxuWfPm9oBMPr7y8ABe",
-	//			"meta": {
-	//				"baz": 123,
-	//				"foo": "bar"
-	//			},
-	//			"nbf": 1728929558,
-	//			"nonce": {
+	//		{
+	//			"h": {
 	//				"/": {
-	//					"bytes": "u0HMgJ5Y+M84I/66"
+	//					"bytes": "NO0BcQ"
 	//				}
 	//			},
-	//			"pol": [
-	//				[
-	//					"==",
-	//					".status",
-	//					"draft"
-	//				],
-	//				[
-	//					"all",
-	//					".reviewer",
+	//			"ucan/dlg@1.0.0-rc.1": {
+	//				"aud": "did:key:z6Mkq5YmbJcTrPExNDi26imrTCpKhepjBFBSHqrBDN2ArPkv",
+	//				"cmd": "/foo/bar",
+	//				"exp": 1728933098,
+	//				"iss": "did:key:z6MkhVFznPeR572rTK51UjoTNpnF8cxuWfPm9oBMPr7y8ABe",
+	//				"meta": {
+	//					"baz": 123,
+	//					"foo": "bar"
+	//				},
+	//				"nbf": 1728929558,
+	//				"nonce": {
+	//					"/": {
+	//						"bytes": "u0HMgJ5Y+M84I/66"
+	//					}
+	//				},
+	//				"pol": [
 	//					[
-	//						"like",
-	//						".email",
-	//						"*@example.com"
-	//					]
-	//				],
-	//				[
-	//					"any",
-	//					".tags",
+	//						"==",
+	//						".status",
+	//						"draft"
+	//					],
 	//					[
-	//						"or",
+	//						"all",
+	//						".reviewer",
 	//						[
+	//							"like",
+	//							".email",
+	//							"*@example.com"
+	//						]
+	//					],
+	//					[
+	//						"any",
+	//						".tags",
+	//						[
+	//							"or",
 	//							[
-	//								"==",
-	//								".",
-	//								"news"
-	//							],
-	//							[
-	//								"==",
-	//								".",
-	//								"press"
+	//								[
+	//									"==",
+	//									".",
+	//									"news"
+	//								],
+	//								[
+	//									"==",
+	//									".",
+	//									"press"
+	//								]
 	//							]
 	//						]
 	//					]
-	//				]
-	//			],
-	//			"sub": "did:key:z6MktA1uBdCpq4uJBqE9jjMiLyxZBg9a6xgPPKJjMqss6Zc2"
+	//				],
+	//				"sub": "did:key:z6MktA1uBdCpq4uJBqE9jjMiLyxZBg9a6xgPPKJjMqss6Zc2"
+	//			}
 	//		}
-	//	}
-	// ]
+	//	]
 }
 
 // The following example shows how to create a UCAN root delegation.Token
 // - a delegation.Token with the subject (sub) set to the value of issuer
 // (iss).
 func ExampleRoot() {
-	issPriv, issPub, err := crypto.GenerateEd25519Key(rand.Reader)
-	printThenPanicOnErr(err)
-
-	issDid, err := did.FromPubKey(issPub)
-	printThenPanicOnErr(err)
-	fmt.Println("issDid:", issDid)
-
-	audDid := did.MustParse(AudienceDID)
-
 	// The command defines the shape of the arguments that will be evaluated against the policy
 	cmd := command.MustParse("/foo/bar")
 
@@ -171,7 +150,7 @@ func ExampleRoot() {
 		)),
 	)
 
-	tkn, err := delegation.Root(issPriv, audDid, cmd, pol,
+	tkn, err := delegation.Root(didtest.PersonaAlice.DID(), didtest.PersonaBob.DID(), cmd, pol,
 		delegation.WithExpirationIn(time.Hour),
 		delegation.WithNotBeforeIn(time.Minute),
 		delegation.WithMeta("foo", "bar"),
@@ -180,7 +159,7 @@ func ExampleRoot() {
 	printThenPanicOnErr(err)
 
 	// "Seal", meaning encode and wrap into a signed envelope.
-	data, id, err := tkn.ToSealed(issPriv)
+	data, id, err := tkn.ToSealed(didtest.PersonaAlice.PrivKey())
 	printThenPanicOnErr(err)
 
 	printCIDAndSealed(id, data)
@@ -189,82 +168,82 @@ func ExampleRoot() {
 	//
 	// issDid: did:key:z6MknWJqz17Y4AfsXSJUFKomuBR4GTkViM7kJYutzTMkCyFF
 	//
-	// CID (base58BTC): zdpuAwLojgfvFCbjz2FsKrvN1khDQ9mFGT6b6pxjMfz73Roed
+	// CID (base58BTC): zdpuAkwYz8nY7uU8j3F6wVTfFY1VEoExwvUAYBEwRWfTozddE
 	//
-	// DAG-CBOR (base64) out: 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
+	// DAG-CBOR (base64) out: 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
 	//
 	// Converted to DAG-JSON out:
-	// [
-	//	{
-	//		"/": {
-	//			"bytes": "6dBhbhhGE36CW22OxjOEIAqdDmBqCNsAhCRljnBdXd7YrVOUG+bnXGCIwd4dTGgpEdmY06PFIl7IXKXCh/ESBg"
-	//		}
-	//	},
-	//	{
-	//		"h": {
+	//	[
+	//		{
 	//			"/": {
-	//				"bytes": "NO0BcQ"
+	//				"bytes": "VpW67FJ+myNi+azvnw2jivuiqXTuMrDZI2Qdaa8jE1Oi3mkjnm7DyqSQGADcomcuDslMWKmJ+OIyvbPG5PtSAw"
 	//			}
 	//		},
-	//		"ucan/dlg@1.0.0-rc.1": {
-	//			"aud": "did:key:z6Mkq5YmbJcTrPExNDi26imrTCpKhepjBFBSHqrBDN2ArPkv",
-	//			"cmd": "/foo/bar",
-	//			"exp": 1728933168,
-	//			"iss": "did:key:z6MknWJqz17Y4AfsXSJUFKomuBR4GTkViM7kJYutzTMkCyFF",
-	//			"meta": {
-	//				"baz": 123,
-	//				"foo": "bar"
-	//			},
-	//			"nbf": 1728929628,
-	//			"nonce": {
+	//		{
+	//			"h": {
 	//				"/": {
-	//					"bytes": "JOsjYi1Pq3OIB0La"
+	//					"bytes": "NO0BcQ"
 	//				}
 	//			},
-	//			"pol": [
-	//				[
-	//					"==",
-	//					".status",
-	//					"draft"
-	//				],
-	//				[
-	//					"all",
-	//					".reviewer",
+	//			"ucan/dlg@1.0.0-rc.1": {
+	//				"aud": "did:key:z6MkvJPmEZZYbgiw1ouT1oouTsTFBHJSts9ophVsNgcRmYxU",
+	//				"cmd": "/foo/bar",
+	//				"exp": 1732568424,
+	//				"iss": "did:key:z6Mkuukk2skDXLQn7NK3Eh9jMndYfvDBxxktgpidJAqb7M3p",
+	//				"meta": {
+	//					"baz": 123,
+	//					"foo": "bar"
+	//				},
+	//				"nbf": 1732564884,
+	//				"nonce": {
+	//					"/": {
+	//						"bytes": "wzDc03WBciJIGPWG"
+	//					}
+	//				},
+	//				"pol": [
 	//					[
-	//						"like",
-	//						".email",
-	//						"*@example.com"
-	//					]
-	//				],
-	//				[
-	//					"any",
-	//					".tags",
+	//						"==",
+	//						".status",
+	//						"draft"
+	//					],
 	//					[
-	//						"or",
+	//						"all",
+	//						".reviewer",
 	//						[
+	//							"like",
+	//							".email",
+	//							"*@example.com"
+	//						]
+	//					],
+	//					[
+	//						"any",
+	//						".tags",
+	//						[
+	//							"or",
 	//							[
-	//								"==",
-	//								".",
-	//								"news"
-	//							],
-	//							[
-	//								"==",
-	//								".",
-	//								"press"
+	//								[
+	//									"==",
+	//									".",
+	//									"news"
+	//								],
+	//								[
+	//									"==",
+	//									".",
+	//									"press"
+	//								]
 	//							]
 	//						]
 	//					]
-	//				]
-	//			],
-	//			"sub": "did:key:z6MknWJqz17Y4AfsXSJUFKomuBR4GTkViM7kJYutzTMkCyFF"
+	//				],
+	//				"sub": "did:key:z6Mkuukk2skDXLQn7NK3Eh9jMndYfvDBxxktgpidJAqb7M3p"
+	//			}
 	//		}
-	//	}
-	// ]
+	//	]
 }
 
 // The following example demonstrates how to get a delegation.Token from
 // a DAG-CBOR []byte.
-func ExampleToken_FromSealed() {
+func ExampleFromSealed() {
 	const cborBase64 = "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"
 
 	cborBytes, err := base64.StdEncoding.DecodeString(cborBase64)
@@ -293,12 +272,14 @@ func ExampleToken_FromSealed() {
 	// Policy (pol): [
 	//   ["==", ".status", "draft"],
 	//   ["all", ".reviewer",
-	//     ["like", ".email", "*@example.com"]],
+	//     ["like", ".email", "*@example.com"]
+	//   ],
 	//   ["any", ".tags",
 	//     ["or", [
 	//       ["==", ".", "news"],
-	//       ["==", ".", "press"]]]
-	//     ]
+	//       ["==", ".", "press"]
+	//     ]]
+	//   ]
 	// ]
 	// Nonce (nonce): 000102030405060708090a0b
 	// Meta (meta): {}

token/delegation/ipld.go

@@ -1,6 +1,7 @@
 package delegation
 
 import (
+	"fmt"
 	"io"
 
 	"github.com/ipfs/go-cid"
@@ -193,8 +194,16 @@ func FromIPLD(node datamodel.Node) (*Token, error) {
 }
 
 func (t *Token) toIPLD(privKey crypto.PrivKey) (datamodel.Node, error) {
-	var sub *string
+	// sanity check that privKey and issuer are matching
+	issPub, err := t.issuer.PubKey()
+	if err != nil {
+		return nil, err
+	}
+	if !issPub.Equals(privKey.GetPublic()) {
+		return nil, fmt.Errorf("private key doesn't match the issuer")
+	}
 
+	var sub *string
 	if t.subject != did.Undef {
 		s := t.subject.String()
 		sub = &s

token/delegation/options.go

@@ -3,8 +3,6 @@ package delegation
 import (
 	"fmt"
 	"time"
-
-	"github.com/ucan-wg/go-ucan/did"
 )
 
 // Option is a type that allows optional fields to be set during the
@@ -44,6 +42,24 @@ func WithMeta(key string, val any) Option {
 	}
 }
 
+// WithEncryptedMetaString adds a key/value pair in the "meta" field.
+// The string value is encrypted with the given key.
+// The ciphertext will be 40 bytes larger than the plaintext due to encryption overhead.
+func WithEncryptedMetaString(key, val string, encryptionKey []byte) Option {
+	return func(t *Token) error {
+		return t.meta.AddEncrypted(key, val, encryptionKey)
+	}
+}
+
+// WithEncryptedMetaBytes adds a key/value pair in the "meta" field.
+// The []byte value is encrypted with the given key.
+// The ciphertext will be 40 bytes larger than the plaintext due to encryption overhead.
+func WithEncryptedMetaBytes(key string, val, encryptionKey []byte) Option {
+	return func(t *Token) error {
+		return t.meta.AddEncrypted(key, val, encryptionKey)
+	}
+}
+
 // WithNotBefore set's the Token's optional "notBefore" field to the value
 // of the provided time.Time.
 func WithNotBefore(nbf time.Time) Option {
@@ -67,20 +83,6 @@ func WithNotBeforeIn(nbf time.Duration) Option {
 	}
 }
 
-// WithSubject sets the Tokens's optional "subject" field to the value of
-// provided did.DID.
-//
-// This Option should only be used with the New constructor - since
-// Subject is a required parameter when creating a Token via the Root
-// constructor, any value provided via this Option will be silently
-// overwritten.
-func WithSubject(sub did.DID) Option {
-	return func(t *Token) error {
-		t.subject = sub
-		return nil
-	}
-}
-
 // WithNonce sets the Token's nonce with the given value.
 // If this option is not used, a random 12-byte nonce is generated for this required field.
 func WithNonce(nonce []byte) Option {

token/delegation/schema.go

@@ -26,17 +26,17 @@ const Tag = "ucan/dlg@1.0.0-rc.1"
 var schemaBytes []byte
 
 var (
-	once sync.Once
-	ts   *schema.TypeSystem
-	err  error
+	once      sync.Once
+	ts        *schema.TypeSystem
+	errSchema error
 )
 
 func mustLoadSchema() *schema.TypeSystem {
 	once.Do(func() {
-		ts, err = ipld.LoadSchemaBytes(schemaBytes)
+		ts, errSchema = ipld.LoadSchemaBytes(schemaBytes)
 	})
-	if err != nil {
-		panic(fmt.Errorf("failed to load IPLD schema: %s", err))
+	if errSchema != nil {
+		panic(fmt.Errorf("failed to load IPLD schema: %s", errSchema))
 	}
 	return ts
 }

token/delegation/schema_test.go

@@ -3,7 +3,6 @@ package delegation_test
 import (
 	"bytes"
 	_ "embed"
-	"fmt"
 	"testing"
 
 	"github.com/ipld/go-ipld-prime"
@@ -11,6 +10,7 @@ import (
 	"github.com/stretchr/testify/require"
 	"gotest.tools/v3/golden"
 
+	"github.com/ucan-wg/go-ucan/did/didtest"
 	"github.com/ucan-wg/go-ucan/token/delegation"
 	"github.com/ucan-wg/go-ucan/token/internal/envelope"
 )
@@ -22,7 +22,7 @@ func TestSchemaRoundTrip(t *testing.T) {
 	t.Parallel()
 
 	delegationJson := golden.Get(t, "new.dagjson")
-	privKey := privKey(t, issuerPrivKeyCfg)
+	privKey := didtest.PersonaAlice.PrivKey()
 
 	t.Run("via buffers", func(t *testing.T) {
 		t.Parallel()
@@ -33,21 +33,19 @@ func TestSchemaRoundTrip(t *testing.T) {
 		p1, err := delegation.FromDagJson(delegationJson)
 		require.NoError(t, err)
 
+		_, newCID, err := p1.ToSealed(privKey)
+		require.NoError(t, err)
+
 		cborBytes, id, err := p1.ToSealed(privKey)
 		require.NoError(t, err)
-		assert.Equal(t, newCID, envelope.CIDToBase58BTC(id))
-		fmt.Println("cborBytes length", len(cborBytes))
-		fmt.Println("cbor", string(cborBytes))
+		assert.Equal(t, envelope.CIDToBase58BTC(newCID), envelope.CIDToBase58BTC(id))
 
 		p2, c2, err := delegation.FromSealed(cborBytes)
 		require.NoError(t, err)
 		assert.Equal(t, id, c2)
-		fmt.Println("read Cbor", p2)
 
 		readJson, err := p2.ToDagJson(privKey)
 		require.NoError(t, err)
-		fmt.Println("readJson length", len(readJson))
-		fmt.Println("json: ", string(readJson))
 
 		assert.JSONEq(t, string(delegationJson), string(readJson))
 	})
@@ -63,11 +61,13 @@ func TestSchemaRoundTrip(t *testing.T) {
 		p1, err := delegation.FromDagJsonReader(buf)
 		require.NoError(t, err)
 
+		_, newCID, err := p1.ToSealed(privKey)
+		require.NoError(t, err)
+
 		cborBytes := &bytes.Buffer{}
 		id, err := p1.ToSealedWriter(cborBytes, privKey)
-		t.Log(len(id.Bytes()), id.Bytes())
 		require.NoError(t, err)
-		assert.Equal(t, newCID, envelope.CIDToBase58BTC(id))
+		assert.Equal(t, envelope.CIDToBase58BTC(newCID), envelope.CIDToBase58BTC(id))
 
 		// buf = bytes.NewBuffer(cborBytes.Bytes())
 		p2, c2, err := delegation.FromSealedReader(cborBytes)
@@ -79,6 +79,16 @@ func TestSchemaRoundTrip(t *testing.T) {
 
 		assert.JSONEq(t, string(delegationJson), readJson.String())
 	})
+
+	t.Run("fails with wrong PrivKey", func(t *testing.T) {
+		t.Parallel()
+
+		p1, err := delegation.FromDagJson(delegationJson)
+		require.NoError(t, err)
+
+		_, _, err = p1.ToSealed(didtest.PersonaBob.PrivKey())
+		require.EqualError(t, err, "private key doesn't match the issuer")
+	})
 }
 
 func BenchmarkSchemaLoad(b *testing.B) {
@@ -90,7 +100,7 @@ func BenchmarkSchemaLoad(b *testing.B) {
 
 func BenchmarkRoundTrip(b *testing.B) {
 	delegationJson := golden.Get(b, "new.dagjson")
-	privKey := privKey(b, issuerPrivKeyCfg)
+	privKey := didtest.PersonaAlice.PrivKey()
 
 	b.Run("via buffers", func(b *testing.B) {
 		p1, _ := delegation.FromDagJson(delegationJson)

token/delegation/testdata/new.dagjson

@@ -1 +1 @@
-[{"/":{"bytes":"FM6otj0r/noJWiGAC5WV86xAazxrF173IihuHJgEt35CtSzjeaelrR3UwaSr8xbE9sLpo5xJhUbo0QLI273hDA"}},{"h":{"/":{"bytes":"NO0BcQ"}},"ucan/dlg@1.0.0-rc.1":{"aud":"did:key:z6Mkq5YmbJcTrPExNDi26imrTCpKhepjBFBSHqrBDN2ArPkv","cmd":"/foo/bar","exp":7258118400,"iss":"did:key:z6Mkpzn2n3ZGT2VaqMGSQC3tzmzV4TS9S71iFsDXE1WnoNH2","meta":{"bar":"barr","foo":"fooo"},"nonce":{"/":{"bytes":"NnJvRGhHaTBraU5yaVFBejdKM2QrYk9lb0kvdGo4RU5pa21RTmJ0am5EMA"}},"pol":[["==",".status","draft"],["all",".reviewer",["like",".email","*@example.com"]],["any",".tags",["or",[["==",".","news"],["==",".","press"]]]]],"sub":"did:key:z6MktA1uBdCpq4uJBqE9jjMiLyxZBg9a6xgPPKJjMqss6Zc2"}}]
+[{"/":{"bytes":"YJsl8EMLnXSFE/nKKjMxz9bHHo+Y7QeLEzukEzW1TB+m53TTiY1aOt+qUO8JaTcOKsOHt/a4Vn+YiOd5CkLdAQ"}},{"h":{"/":{"bytes":"NO0BcQ"}},"ucan/dlg@1.0.0-rc.1":{"aud":"did:key:z6MkvJPmEZZYbgiw1ouT1oouTsTFBHJSts9ophVsNgcRmYxU","cmd":"/foo/bar","exp":7258118400,"iss":"did:key:z6Mkuukk2skDXLQn7NK3Eh9jMndYfvDBxxktgpidJAqb7M3p","meta":{"bar":"barr","foo":"fooo"},"nonce":{"/":{"bytes":"NnJvRGhHaTBraU5yaVFBejdKM2QrYk9lb0kvdGo4RU5pa21RTmJ0am5EMA"}},"pol":[["==",".status","draft"],["all",".reviewer",["like",".email","*@example.com"]],["any",".tags",["or",[["==",".","news"],["==",".","press"]]]]],"sub":"did:key:z6Mkgupchh5HwuHahS7YsyE8bLua1Mr8p2iKNRhyvSvRAs9n"}}]

token/delegation/testdata/powerline.dagjson

@@ -0,0 +1 @@
+[{"/":{"bytes":"i3YkPDvNSU4V8XYEluZhLH0b+NDcW/6+PtPSUHC17cmXXqgelG0K4EzWQQkS9UsYCHfkZSCn9NjGSXYMMFhaAQ"}},{"h":{"/":{"bytes":"NO0BcQ"}},"ucan/dlg@1.0.0-rc.1":{"aud":"did:key:z6MkvJPmEZZYbgiw1ouT1oouTsTFBHJSts9ophVsNgcRmYxU","cmd":"/foo/bar","exp":7258118400,"iss":"did:key:z6Mkuukk2skDXLQn7NK3Eh9jMndYfvDBxxktgpidJAqb7M3p","meta":{"bar":"barr","foo":"fooo"},"nonce":{"/":{"bytes":"NnJvRGhHaTBraU5yaVFBejdKM2QrYk9lb0kvdGo4RU5pa21RTmJ0am5EMA"}},"pol":[["==",".status","draft"],["all",".reviewer",["like",".email","*@example.com"]],["any",".tags",["or",[["==",".","news"],["==",".","press"]]]]]}}]

token/delegation/testdata/root.dagjson

@@ -1 +1 @@
-[{"/":{"bytes":"aYBq08tfm0zQZnPg/5tB9kM5mklRU9PPIkV7CK68jEgbd76JbCGuu75vfLyBu3WTqKzLSJ583pbwu668m/7MBQ"}},{"h":{"/":{"bytes":"NO0BcQ"}},"ucan/dlg@1.0.0-rc.1":{"aud":"did:key:z6Mkq5YmbJcTrPExNDi26imrTCpKhepjBFBSHqrBDN2ArPkv","cmd":"/foo/bar","exp":7258118400,"iss":"did:key:z6Mkpzn2n3ZGT2VaqMGSQC3tzmzV4TS9S71iFsDXE1WnoNH2","meta":{"bar":"barr","foo":"fooo"},"nonce":{"/":{"bytes":"NnJvRGhHaTBraU5yaVFBejdKM2QrYk9lb0kvdGo4RU5pa21RTmJ0am5EMA"}},"pol":[["==",".status","draft"],["all",".reviewer",["like",".email","*@example.com"]],["any",".tags",["or",[["==",".","news"],["==",".","press"]]]]],"sub":"did:key:z6Mkpzn2n3ZGT2VaqMGSQC3tzmzV4TS9S71iFsDXE1WnoNH2"}}]
+[{"/":{"bytes":"BBabgnWqd+cjwG1td0w9BudNocmUwoR89RMZTqZHk3osCXEI/bOkko0zTvlusaE4EMBBeSzZDKzjvunLBfdiBg"}},{"h":{"/":{"bytes":"NO0BcQ"}},"ucan/dlg@1.0.0-rc.1":{"aud":"did:key:z6MkvJPmEZZYbgiw1ouT1oouTsTFBHJSts9ophVsNgcRmYxU","cmd":"/foo/bar","exp":7258118400,"iss":"did:key:z6Mkuukk2skDXLQn7NK3Eh9jMndYfvDBxxktgpidJAqb7M3p","meta":{"bar":"barr","foo":"fooo"},"nonce":{"/":{"bytes":"NnJvRGhHaTBraU5yaVFBejdKM2QrYk9lb0kvdGo4RU5pa21RTmJ0am5EMA"}},"pol":[["==",".status","draft"],["all",".reviewer",["like",".email","*@example.com"]],["any",".tags",["or",[["==",".","news"],["==",".","press"]]]]],"sub":"did:key:z6Mkuukk2skDXLQn7NK3Eh9jMndYfvDBxxktgpidJAqb7M3p"}}]

token/delegation/utilities.go

@@ -0,0 +1,24 @@
+package delegation
+
+import (
+	"fmt"
+
+	"github.com/ipfs/go-cid"
+)
+
+// ErrDelegationNotFound is returned if a delegation token is not found
+var ErrDelegationNotFound = fmt.Errorf("delegation not found")
+
+// Loader is a delegation token loader.
+type Loader interface {
+	// GetDelegation returns the delegation.Token matching the given CID.
+	// If not found, ErrDelegationNotFound is returned.
+	GetDelegation(cid cid.Cid) (*Token, error)
+}
+
+// Bundle carries together a decoded token with its Cid and raw signed data.
+type Bundle struct {
+	Cid     cid.Cid
+	Decoded *Token
+	Sealed  []byte
+}

token/interface.go

@@ -2,22 +2,22 @@ package token
 
 import (
 	"io"
+	"time"
 
 	"github.com/ipfs/go-cid"
 	"github.com/ipld/go-ipld-prime/codec"
 	"github.com/libp2p/go-libp2p/core/crypto"
-
-	"github.com/ucan-wg/go-ucan/did"
-	"github.com/ucan-wg/go-ucan/pkg/meta"
 )
 
 type Token interface {
 	Marshaller
 
-	// Issuer returns the did.DID representing the Token's issuer.
-	Issuer() did.DID
-	// Meta returns the Token's metadata.
-	Meta() meta.ReadOnly
+	// IsValidNow verifies that the token can be used at the current time, based on expiration or "not before" fields.
+	// This does NOT do any other kind of verifications.
+	IsValidNow() bool
+	// IsValidNow verifies that the token can be used at the given time, based on expiration or "not before" fields.
+	// This does NOT do any other kind of verifications.
+	IsValidAt(t time.Time) bool
 }
 
 type Marshaller interface {
@@ -39,3 +39,10 @@ type Marshaller interface {
 	// ToDagJsonWriter is the same as ToDagJson, but it accepts an io.Writer.
 	ToDagJsonWriter(w io.Writer, privKey crypto.PrivKey) error
 }
+
+// Bundle carries together a decoded token with its Cid and raw signed data.
+type Bundle struct {
+	Cid     cid.Cid
+	Decoded Token
+	Sealed  []byte
+}

token/internal/envelope/example_test.go

@@ -41,18 +41,18 @@ const (
 var schemaBytes []byte
 
 var (
-	once sync.Once
-	ts   *schema.TypeSystem
-	err  error
+	once      sync.Once
+	ts        *schema.TypeSystem
+	errSchema error
 )
 
 func mustLoadSchema() *schema.TypeSystem {
 	once.Do(func() {
-		ts, err = ipld.LoadSchemaBytes(schemaBytes)
+		ts, errSchema = ipld.LoadSchemaBytes(schemaBytes)
 	})
 
-	if err != nil {
-		panic(fmt.Errorf("failed to load IPLD schema: %s", err))
+	if errSchema != nil {
+		panic(fmt.Errorf("failed to load IPLD schema: %s", errSchema))
 	}
 
 	return ts

token/internal/envelope/ipld.go

@@ -187,6 +187,7 @@ func FromIPLD[T Tokener](node datamodel.Node) (T, error) {
 		return zero, errors.New("the VarsigHeader key type doesn't match the issuer's key type")
 	}
 
+	// TODO: can we use the already serialized CBOR data here, instead of encoding again the payload?
 	data, err := ipld.Encode(info.sigPayloadNode, dagcbor.Encode)
 	if err != nil {
 		return zero, err

token/internal/nonce/nonce.go

@@ -0,0 +1,31 @@
+package nonce
+
+import "crypto/rand"
+
+// TODO: some crypto scheme require more, is that our case?
+//
+// The spec mention:
+// The REQUIRED nonce parameter nonce MAY be any value.
+// A randomly generated string is RECOMMENDED to provide a unique UCAN, though it MAY
+// also be a monotonically increasing count of the number of links in the hash chain.
+// This field helps prevent replay attacks and ensures a unique CID per delegation.
+// The iss, aud, and exp fields together will often ensure that UCANs are unique,
+// but adding the nonce ensures uniqueness.
+//
+// The recommended size of the nonce differs by key type. In many cases, a random
+// 12-byte nonce is sufficient. If uncertain, check the nonce in your DID's crypto suite.
+//
+// 12 bytes is 10^28, 16 bytes is 10^38. Both sounds like a lot of random to achieve
+// those goals, but maybe the crypto voodoo require more.
+//
+// The rust implementation use 16 bytes nonce.
+
+// Generate creates a 12-byte random nonce.
+func Generate() ([]byte, error) {
+	res := make([]byte, 12)
+	_, err := rand.Read(res)
+	if err != nil {
+		return nil, err
+	}
+	return res, nil
+}

token/internal/parse/parse.go

@@ -0,0 +1,29 @@
+package parse
+
+import (
+	"fmt"
+	"time"
+
+	"github.com/ucan-wg/go-ucan/did"
+	"github.com/ucan-wg/go-ucan/pkg/policy/limits"
+)
+
+func OptionalDID(s *string) (did.DID, error) {
+	if s == nil {
+		return did.Undef, nil
+	}
+	return did.Parse(*s)
+}
+
+func OptionalTimestamp(sec *int64) (*time.Time, error) {
+	if sec == nil {
+		return nil, nil
+	}
+
+	if *sec > limits.MaxInt53 || *sec < limits.MinInt53 {
+		return nil, fmt.Errorf("timestamp value %d exceeds safe integer bounds", *sec)
+	}
+
+	t := time.Unix(*sec, 0)
+	return &t, nil
+}

token/internal/parse/parse_test.go

@@ -0,0 +1,64 @@
+package parse
+
+import (
+	"testing"
+
+	"github.com/stretchr/testify/require"
+	"github.com/ucan-wg/go-ucan/pkg/policy/limits"
+)
+
+func TestOptionalTimestamp(t *testing.T) {
+	tests := []struct {
+		name    string
+		input   *int64
+		wantErr bool
+	}{
+		{
+			name:    "nil timestamp",
+			input:   nil,
+			wantErr: false,
+		},
+		{
+			name:    "valid timestamp",
+			input:   int64Ptr(1625097600),
+			wantErr: false,
+		},
+		{
+			name:    "max safe integer",
+			input:   int64Ptr(limits.MaxInt53),
+			wantErr: false,
+		},
+		{
+			name:    "exceeds max safe integer",
+			input:   int64Ptr(limits.MaxInt53 + 1),
+			wantErr: true,
+		},
+		{
+			name:    "below min safe integer",
+			input:   int64Ptr(limits.MinInt53 - 1),
+			wantErr: true,
+		},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			result, err := OptionalTimestamp(tt.input)
+			if tt.wantErr {
+				require.Error(t, err)
+				require.Contains(t, err.Error(), "exceeds safe integer bounds")
+				require.Nil(t, result)
+			} else {
+				require.NoError(t, err)
+				if tt.input == nil {
+					require.Nil(t, result)
+				} else {
+					require.NotNil(t, result)
+				}
+			}
+		})
+	}
+}
+
+func int64Ptr(i int64) *int64 {
+	return &i
+}

token/invocation/errors.go

@@ -0,0 +1,41 @@
+package invocation
+
+import "errors"
+
+// Loading errors
+var (
+	// ErrMissingDelegation
+	ErrMissingDelegation = errors.New("loader missing delegation for proof chain")
+)
+
+// Time bound errors
+var (
+	// ErrTokenExpired is returned if a token is invalid at execution time
+	ErrTokenInvalidNow = errors.New("token has expired")
+)
+
+// Principal alignment errors
+var (
+	// ErrNoProof is returned when no delegations were provided to prove
+	// that the invocation should be executed.
+	ErrNoProof = errors.New("at least one delegation must be provided to validate the invocation")
+
+	// ErrLastNotRoot is returned if the last delegation token in the proof
+	// chain is not a root delegation token.
+	ErrLastNotRoot = errors.New("the last delegation token in proof chain must be a root token")
+
+	// ErrBrokenChain is returned when the Audience of a delegation is
+	// not the Issuer of the previous one.
+	ErrBrokenChain = errors.New("delegation proof chain doesn't connect the invocation to the subject")
+
+	// ErrWrongSub is returned when the Subject of a delegation is not the invocation audience.
+	ErrWrongSub = errors.New("delegation subject need to match the invocation audience")
+
+	// ErrCommandNotCovered is returned when a delegation command doesn't cover (identical or parent of) the
+	// next delegation or invocation's command.
+	ErrCommandNotCovered = errors.New("allowed command doesn't cover the next delegation or invocation")
+)
+
+// ErrPolicyNotSatisfied is returned when the provided Arguments don't
+// satisfy one or more of the aggregated Policy Statements
+var ErrPolicyNotSatisfied = errors.New("the following UCAN policy is not satisfied")

token/invocation/examples_test.go

@@ -0,0 +1,201 @@
+package invocation_test
+
+import (
+	"bytes"
+	"encoding/json"
+	"errors"
+	"fmt"
+	"time"
+
+	"github.com/ipfs/go-cid"
+	"github.com/ipld/go-ipld-prime"
+	"github.com/ipld/go-ipld-prime/codec/dagcbor"
+	"github.com/ipld/go-ipld-prime/codec/dagjson"
+	"github.com/ipld/go-ipld-prime/node/basicnode"
+	"github.com/libp2p/go-libp2p/core/crypto"
+
+	"github.com/ucan-wg/go-ucan/did"
+	"github.com/ucan-wg/go-ucan/pkg/command"
+	"github.com/ucan-wg/go-ucan/token/invocation"
+)
+
+func ExampleNew() {
+	privKey, iss, sub, cmd, args, prf, meta, err := setupExampleNew()
+	if err != nil {
+		fmt.Println("failed to create setup:", err.Error())
+
+		return
+	}
+
+	inv, err := invocation.New(iss, cmd, sub, prf,
+		invocation.WithArgument("uri", args["uri"]),
+		invocation.WithArgument("headers", args["headers"]),
+		invocation.WithArgument("payload", args["payload"]),
+		invocation.WithMeta("env", "development"),
+		invocation.WithMeta("tags", meta["tags"]),
+		invocation.WithExpirationIn(time.Minute),
+		invocation.WithoutInvokedAt())
+	if err != nil {
+		fmt.Println("failed to create invocation:", err.Error())
+
+		return
+	}
+
+	data, cid, err := inv.ToSealed(privKey)
+	if err != nil {
+		fmt.Println("failed to seal invocation:", err.Error())
+
+		return
+	}
+
+	json, err := prettyDAGJSON(data)
+	if err != nil {
+		fmt.Println("failed to pretty DAG-JSON:", err.Error())
+
+		return
+	}
+
+	fmt.Println("CID:", cid)
+	fmt.Println("Token (pretty DAG-JSON):")
+	fmt.Println(json)
+
+	// Expected CID and DAG-JSON output:
+	// CID: bafyreid2n5q45vk4osned7k5huocbe3mxbisonh5vujepqftc5ftr543ae
+	// Token (pretty DAG-JSON):
+	// [
+	//   {
+	// 	"/": {
+	// 	  "bytes": "gvyL7kdSkgmaDpDU/Qj9ohRwxYLCHER52HFMSFEqQqEcQC9qr4JCPP1f/WybvGGuVzYiA0Hx4JO+ohNz8BxUAA"
+	// 	}
+	//   },
+	//   {
+	// 	"h": {
+	// 	  "/": {
+	// 		"bytes": "NO0BcQ"
+	// 	  }
+	// 	},
+	// 	"ucan/inv@1.0.0-rc.1": {
+	// 	  "args": {
+	// 		"headers": {
+	// 		  "Content-Type": "application/json"
+	// 		},
+	// 		"payload": {
+	// 		  "body": "UCAN is great",
+	// 		  "draft": true,
+	// 		  "title": "UCAN for Fun and Profit",
+	// 		  "topics": [
+	// 			"authz",
+	// 			"journal"
+	// 		  ]
+	// 		},
+	// 		"uri": "https://example.com/blog/posts"
+	// 	  },
+	// 	  "cmd": "/crud/create",
+	// 	  "exp": 1729788921,
+	// 	  "iss": "did:key:z6MkhniGGyP88eZrq2dpMvUPdS2RQMhTUAWzcu6kVGUvEtCJ",
+	// 	  "meta": {
+	// 		"env": "development",
+	// 		"tags": [
+	// 		  "blog",
+	// 		  "post",
+	// 		  "pr#123"
+	// 		]
+	// 	  },
+	// 	  "nonce": {
+	// 		"/": {
+	// 		  "bytes": "2xXPoZwWln1TfXIp"
+	// 		}
+	// 	  },
+	// 	  "prf": [
+	// 		{
+	// 		  "/": "bafyreigx3qxd2cndpe66j2mdssj773ecv7tqd7wovcnz5raguw6lj7sjoe"
+	// 		},
+	// 		{
+	// 		  "/": "bafyreib34ira254zdqgehz6f2bhwme2ja2re3ltcalejv4x4tkcveujvpa"
+	// 		},
+	// 		{
+	// 		  "/": "bafyreibkb66tpo2ixqx3fe5hmekkbuasrod6olt5bwm5u5pi726mduuwlq"
+	// 		}
+	// 	  ],
+	// 	  "sub": "did:key:z6MktWuvPvBe5UyHnDGuEdw8aJ5qrhhwLG6jy7cQYM6ckP6P"
+	// 	}
+	//   }
+	// ]
+}
+
+func prettyDAGJSON(data []byte) (string, error) {
+	var node ipld.Node
+
+	node, err := ipld.Decode(data, dagcbor.Decode)
+	if err != nil {
+		return "", err
+	}
+
+	jsonData, err := ipld.Encode(node, dagjson.Encode)
+	if err != nil {
+		return "", err
+	}
+
+	var out bytes.Buffer
+	if err := json.Indent(&out, jsonData, "", "  "); err != nil {
+		return "", err
+	}
+
+	return out.String(), nil
+}
+
+func setupExampleNew() (privKey crypto.PrivKey, iss, sub did.DID, cmd command.Command, args map[string]any, prf []cid.Cid, meta map[string]any, errs error) {
+	var err error
+
+	privKey, iss, err = did.GenerateEd25519()
+	if err != nil {
+		errs = errors.Join(errs, fmt.Errorf("failed to generate Issuer identity: %w", err))
+	}
+
+	_, sub, err = did.GenerateEd25519()
+	if err != nil {
+		errs = errors.Join(errs, fmt.Errorf("failed to generate Subject identity: %w", err))
+	}
+
+	cmd, err = command.Parse("/crud/create")
+	if err != nil {
+		errs = errors.Join(errs, fmt.Errorf("failed to parse command: %w", err))
+	}
+
+	headers := map[string]string{
+		"Content-Type": "application/json",
+	}
+
+	payload := map[string]any{
+		"body":   "UCAN is great",
+		"draft":  true,
+		"title":  "UCAN for Fun and Profit",
+		"topics": []string{"authz", "journal"},
+	}
+
+	args = map[string]any{
+		// you can also directly pass IPLD values
+		"uri":     basicnode.NewString("https://example.com/blog/posts"),
+		"headers": headers,
+		"payload": payload,
+	}
+
+	prf = make([]cid.Cid, 3)
+	for i, v := range []string{
+		"zdpuAzx4sBrBCabrZZqXgvK3NDzh7Mf5mKbG11aBkkMCdLtCp",
+		"zdpuApTCXfoKh2sB1KaUaVSGofCBNPUnXoBb6WiCeitXEibZy",
+		"zdpuAoFdXRPw4n6TLcncoDhq1Mr6FGbpjAiEtqSBrTSaYMKkf",
+	} {
+		prf[i], err = cid.Parse(v)
+		if err != nil {
+			errs = errors.Join(errs, fmt.Errorf("failed to parse proof cid: %w", err))
+		}
+	}
+
+	meta = map[string]any{
+		"env":  basicnode.NewString("development"),
+		"tags": []string{"blog", "post", "pr#123"},
+	}
+
+	return // WARNING: named return values
+}