Merge pull request #73 from ucan-wg/dlg-constructor

delegation: WIP harmonisation of the constructors, issuer verification

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
+- 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.

did/didtest/crypto.go

@@ -0,0 +1,127 @@
+// 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"
+	"testing"
+
+	"github.com/libp2p/go-libp2p/core/crypto"
+	"github.com/stretchr/testify/require"
+
+	"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
+	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 {
+	return privKeys[p]
+}
+
+// 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(t *testing.T) string {
+	pubKeyMar, err := crypto.MarshalPublicKey(p.PrivKey().GetPublic())
+	require.NoError(t, 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,
+	}
+}

go.mod

@@ -3,6 +3,7 @@ module github.com/ucan-wg/go-ucan
 go 1.23
 
 require (
+	github.com/dave/jennifer v1.7.1
 	github.com/decred/dcrd/dcrec/secp256k1/v4 v4.3.0
 	github.com/ipfs/go-cid v0.4.1
 	github.com/ipld/go-ipld-prime v0.21.0

go.sum

@@ -1,5 +1,7 @@
 github.com/BurntSushi/toml v0.3.1/go.mod h1:xHWCNGjB5oqiDr8zfno3MHue2Ht5sIBksp03qcyfWMU=
 github.com/cpuguy83/go-md2man/v2 v2.0.0-20190314233015-f79a8a8ca69d/go.mod h1:maD7wRr/U5Z6m/iR4s+kqSMx2CaBsrgA7czyZG/E6dU=
+github.com/dave/jennifer v1.7.1 h1:B4jJJDHelWcDhlRQxWeo0Npa/pYKBLrirAQoTN45txo=
+github.com/dave/jennifer v1.7.1/go.mod h1:nXbxhEmQfOZhWml3D1cDK5M1FLnMSozpbFN/m3RmGZc=
 github.com/davecgh/go-spew v1.1.0/go.mod h1:J7Y8YcW2NihsgmVo/mv3lAwl/skON4iLHjSsI+c5H38=
 github.com/davecgh/go-spew v1.1.1 h1:vj9j/u1bqnvCEfJOwUhtlOARqs3+rkHYY13jYWTU97c=
 github.com/davecgh/go-spew v1.1.1/go.mod h1:J7Y8YcW2NihsgmVo/mv3lAwl/skON4iLHjSsI+c5H38=

pkg/args/args.go

@@ -0,0 +1,137 @@
+// 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 (
+	"fmt"
+	"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/literal"
+)
+
+// 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{},
+	}
+}
+
+// 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
+	}
+
+	a.Values[key] = node
+	a.Keys = append(a.Keys, key)
+
+	return nil
+}
+
+// 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 *Args) {
+	for _, key := range other.Keys {
+		if _, ok := a.Values[key]; ok {
+			// don't overwrite
+			continue
+		}
+		a.Values[key] = other.Values[key]
+		a.Keys = append(a.Keys, key)
+	}
+}
+
+// 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
+}

pkg/args/args_test.go

@@ -0,0 +1,179 @@
+package args_test
+
+import (
+	"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/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/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()))
+}
+
+const (
+	argsSchema = "type Args { String : Any }"
+	argsName   = "Args"
+)
+
+var (
+	once sync.Once
+	ts   *schema.TypeSystem
+	err  error
+)
+
+func argsType() schema.Type {
+	once.Do(func() {
+		ts, err = ipld.LoadSchemaBytes([]byte(argsSchema))
+	})
+	if err != nil {
+		panic(err)
+	}
+
+	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/readonly.go

@@ -0,0 +1,23 @@
+package args
+
+import "github.com/ipld/go-ipld-prime"
+
+type ReadOnly struct {
+	args *Args
+}
+
+func (r ReadOnly) ToIPLD() (ipld.Node, error) {
+	return r.args.ToIPLD()
+}
+
+func (r ReadOnly) Equals(other *Args) bool {
+	return r.args.Equals(other)
+}
+
+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/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/reader.go

@@ -2,6 +2,7 @@ package container
 
 import (
 	"encoding/base64"
+	"errors"
 	"fmt"
 	"io"
 	"iter"
@@ -34,13 +35,16 @@ func (ctn Reader) GetToken(cid cid.Cid) (token.Token, error) {
 // 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 errors.Is(err, ErrNotFound) {
+		return nil, delegation.ErrDelegationNotFound
+	}
 	if err != nil {
 		return nil, err
 	}
 	if tkn, ok := tkn.(*delegation.Token); ok {
 		return tkn, nil
 	}
-	return nil, fmt.Errorf("not a delegation token")
+	return nil, delegation.ErrDelegationNotFound
 }
 
 // GetAllDelegations returns all the delegation.Token in the container.
@@ -98,15 +102,36 @@ func FromCbor(r io.Reader) (Reader, error) {
 	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 != currentContainerVersion {
+		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
 		}

pkg/container/serial_test.go

@@ -166,7 +166,7 @@ func randToken() (*delegation.Token, cid.Cid, []byte) {
 		opts = append(opts, delegation.WithMeta(randomString(8), randomString(10)))
 	}
 
-	t, err := delegation.New(priv, aud, cmd, pol, opts...)
+	t, err := delegation.New(iss, aud, cmd, pol, opts...)
 	if err != nil {
 		panic(err)
 	}
@@ -176,3 +176,30 @@ 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++ {
+			_, c, data := randToken()
+			writer.AddSealed(c, data)
+		}
+		buf := bytes.NewBuffer(nil)
+		err := writer.ToCbor(buf)
+		require.NoError(f, err)
+
+		f.Add(buf.Bytes())
+	}
+
+	f.Fuzz(func(t *testing.T, data []byte) {
+		start := time.Now()
+
+		// search for panics
+		_, _ = FromCbor(bytes.NewReader(data))
+
+		if time.Since(start) > 100*time.Millisecond {
+			panic("too long")
+		}
+	})
+}

pkg/container/writer.go

@@ -14,6 +14,8 @@ import (
 
 // TODO: should we have a multibase to wrap the cbor? but there is no reader/write in go-multibase :-(
 
+const currentContainerVersion = "ctn-v1"
+
 // Writer is a token container writer. It provides a convenient way to aggregate and serialize tokens together.
 type Writer map[cid.Cid][]byte
 
@@ -43,10 +45,12 @@ func (ctn Writer) ToCarBase64(w io.Writer) error {
 }
 
 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))
-		}
+	node, err := qp.BuildMap(basicnode.Prototype.Any, 1, func(ma datamodel.MapAssembler) {
+		qp.MapEntry(ma, currentContainerVersion, qp.List(int64(len(ctn)), func(la datamodel.ListAssembler) {
+			for _, bytes := range ctn {
+				qp.ListEntry(la, qp.Bytes(bytes))
+			}
+		}))
 	})
 	if err != nil {
 		return err

pkg/meta/internal/crypto/aes.go

@@ -0,0 +1,132 @@
+package crypto
+
+import (
+	"crypto/aes"
+	"crypto/cipher"
+	"crypto/rand"
+	"errors"
+	"fmt"
+	"io"
+)
+
+// KeySize represents valid AES key sizes
+type KeySize int
+
+const (
+	KeySize128 KeySize = 16 // AES-128
+	KeySize192 KeySize = 24 // AES-192
+	KeySize256 KeySize = 32 // AES-256 (recommended)
+)
+
+// IsValid returns true if the key size is valid for AES
+func (ks KeySize) IsValid() bool {
+	switch ks {
+	case KeySize128, KeySize192, KeySize256:
+		return true
+	default:
+		return false
+	}
+}
+
+var ErrShortCipherText = errors.New("ciphertext too short")
+var ErrNoEncryptionKey = errors.New("encryption key is required")
+var ErrInvalidKeySize = errors.New("invalid key size: must be 16, 24, or 32 bytes")
+var ErrZeroKey = errors.New("encryption key cannot be all zeros")
+
+// GenerateKey generates a random AES key of default size KeySize256 (32 bytes).
+// Returns an error if the specified size is invalid or if key generation fails.
+func GenerateKey() ([]byte, error) {
+	return GenerateKeyWithSize(KeySize256)
+}
+
+// GenerateKeyWithSize generates a random AES key of the specified size.
+// Returns an error if the specified size is invalid or if key generation fails.
+func GenerateKeyWithSize(size KeySize) ([]byte, error) {
+	if !size.IsValid() {
+		return nil, ErrInvalidKeySize
+	}
+
+	key := make([]byte, size)
+	if _, err := io.ReadFull(rand.Reader, key); err != nil {
+		return nil, fmt.Errorf("failed to generate AES key: %w", err)
+	}
+
+	return key, nil
+}
+
+// EncryptWithAESKey encrypts data using AES-GCM with the provided key.
+// The key must be 16, 24, or 32 bytes long (for AES-128, AES-192, or AES-256).
+// Returns the encrypted data with the nonce prepended, or an error if encryption fails.
+func EncryptWithAESKey(data, key []byte) ([]byte, error) {
+	if err := validateAESKey(key); err != nil {
+		return nil, err
+	}
+
+	block, err := aes.NewCipher(key)
+	if err != nil {
+		return nil, err
+	}
+
+	gcm, err := cipher.NewGCM(block)
+	if err != nil {
+		return nil, err
+	}
+
+	nonce := make([]byte, gcm.NonceSize())
+	if _, err = io.ReadFull(rand.Reader, nonce); err != nil {
+		return nil, err
+	}
+
+	return gcm.Seal(nonce, nonce, data, nil), nil
+}
+
+// DecryptStringWithAESKey decrypts data that was encrypted with EncryptWithAESKey.
+// The key must match the one used for encryption.
+// Expects the input to have a prepended nonce.
+// Returns the decrypted data or an error if decryption fails.
+func DecryptStringWithAESKey(data, key []byte) ([]byte, error) {
+	if err := validateAESKey(key); err != nil {
+		return nil, err
+	}
+
+	block, err := aes.NewCipher(key)
+	if err != nil {
+		return nil, err
+	}
+
+	gcm, err := cipher.NewGCM(block)
+	if err != nil {
+		return nil, err
+	}
+
+	if len(data) < gcm.NonceSize() {
+		return nil, ErrShortCipherText
+	}
+
+	nonce, ciphertext := data[:gcm.NonceSize()], data[gcm.NonceSize():]
+	decrypted, err := gcm.Open(nil, nonce, ciphertext, nil)
+	if err != nil {
+		return nil, err
+	}
+
+	return decrypted, nil
+}
+
+func validateAESKey(key []byte) error {
+	if key == nil {
+		return ErrNoEncryptionKey
+	}
+
+	if !KeySize(len(key)).IsValid() {
+		return ErrInvalidKeySize
+	}
+
+	// check if key is all zeros
+	for _, b := range key {
+		if b != 0 {
+			return nil
+		}
+	}
+
+	return ErrZeroKey
+}

pkg/meta/internal/crypto/aes_test.go

@@ -0,0 +1,124 @@
+package crypto
+
+import (
+	"bytes"
+	"crypto/rand"
+	"testing"
+
+	"github.com/stretchr/testify/require"
+)
+
+func TestAESEncryption(t *testing.T) {
+	t.Parallel()
+
+	key := make([]byte, 32) // generated 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, 31),
+			wantErr: ErrInvalidKeySize,
+		},
+		{
+			name:    "zero key returns error",
+			data:    []byte("hello world"),
+			key:     make([]byte, 32),
+			wantErr: ErrZeroKey,
+		},
+	}
+
+	for _, tt := range tests {
+		tt := tt
+		t.Run(tt.name, func(t *testing.T) {
+			t.Parallel()
+
+			encrypted, err := EncryptWithAESKey(tt.data, tt.key)
+			if tt.wantErr != nil {
+				require.ErrorIs(t, err, tt.wantErr)
+
+				return
+			}
+			require.NoError(t, err)
+
+			decrypted, err := DecryptStringWithAESKey(encrypted, tt.key)
+			require.NoError(t, err)
+
+			if tt.key == nil {
+				require.Equal(t, tt.data, encrypted)
+				require.Equal(t, tt.data, decrypted)
+			} else {
+				require.NotEqual(t, tt.data, encrypted)
+				require.True(t, bytes.Equal(tt.data, decrypted))
+			}
+		})
+	}
+}
+
+func TestDecryptionErrors(t *testing.T) {
+	t.Parallel()
+
+	key := make([]byte, 32)
+	_, err := rand.Read(key)
+	require.NoError(t, err)
+
+	tests := []struct {
+		name   string
+		data   []byte
+		key    []byte
+		errMsg string
+	}{
+		{
+			name:   "short ciphertext",
+			data:   []byte("short"),
+			key:    key,
+			errMsg: "ciphertext too short",
+		},
+		{
+			name:   "invalid ciphertext",
+			data:   make([]byte, 16), // just nonce size
+			key:    key,
+			errMsg: "message authentication failed",
+		},
+		{
+			name:   "missing key",
+			data:   []byte("<22>`M<><4D><EFBFBD>l\u001AIF<49>\u0012<31><32><EFBFBD>=h<>?<3F>c<EFBFBD> <20><>\u0012<31><32><EFBFBD><EFBFBD>\u001C<31>\u0018Ƽ(g"),
+			key:    nil,
+			errMsg: "encryption key is required",
+		},
+	}
+
+	for _, tt := range tests {
+		tt := tt
+		t.Run(tt.name, func(t *testing.T) {
+			t.Parallel()
+
+			_, err := DecryptStringWithAESKey(tt.data, tt.key)
+			require.Error(t, err)
+			require.Contains(t, err.Error(), tt.errMsg)
+		})
+	}
+}

pkg/meta/meta.go

@@ -1,24 +1,28 @@
 package meta
 
 import (
+	"errors"
 	"fmt"
-	"reflect"
 	"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/meta/internal/crypto"
+	"github.com/ucan-wg/go-ucan/pkg/policy/literal"
 )
 
-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 +54,21 @@ 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 := crypto.DecryptStringWithAESKey(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.
@@ -83,6 +102,21 @@ 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 := crypto.DecryptStringWithAESKey(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.
@@ -95,35 +129,48 @@ 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.
+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 = crypto.EncryptWithAESKey([]byte(val), encryptionKey)
+		if err != nil {
+			return err
+		}
+	case []byte:
+		encrypted, err = crypto.EncryptWithAESKey(val, encryptionKey)
+		if err != nil {
+			return err
+		}
+	default:
+		return ErrNotEncryptable
+	}
+
+	return m.Add(key, encrypted)
+}
+
 // Equals tells if two Meta hold the same key/values.
 func (m *Meta) Equals(other *Meta) bool {
 	if len(m.Keys) != len(other.Keys) {
@@ -144,18 +191,19 @@ func (m *Meta) String() string {
 	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()
 }
 
@@ -163,15 +211,3 @@ func (m *Meta) String() string {
 func (m *Meta) ReadOnly() ReadOnly {
 	return ReadOnly{m: m}
 }
-
-func fqtn(val any) string {
-	var name string
-
-	t := reflect.TypeOf(val)
-	for t.Kind() == reflect.Pointer {
-		name += "*"
-		t = t.Elem()
-	}
-
-	return name + t.PkgPath() + "." + t.Name()
-}

pkg/meta/meta_test.go

@@ -1,10 +1,10 @@
 package meta_test
 
 import (
+	"crypto/rand"
 	"testing"
 
 	"github.com/stretchr/testify/require"
-	"gotest.tools/v3/assert"
 
 	"github.com/ucan-wg/go-ucan/pkg/meta"
 )
@@ -14,11 +14,64 @@ 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")
+		})
 	})
 }

pkg/meta/readonly.go

@@ -17,6 +17,10 @@ func (r ReadOnly) GetString(key string) (string, error) {
 	return r.m.GetString(key)
 }
 
+func (r ReadOnly) GetEncryptedString(key string, encryptionKey []byte) (string, error) {
+	return r.m.GetEncryptedString(key, encryptionKey)
+}
+
 func (r ReadOnly) GetInt64(key string) (int64, error) {
 	return r.m.GetInt64(key)
 }
@@ -29,6 +33,10 @@ func (r ReadOnly) GetBytes(key string) ([]byte, error) {
 	return r.m.GetBytes(key)
 }
 
+func (r ReadOnly) GetEncryptedBytes(key string, encryptionKey []byte) ([]byte, error) {
+	return r.m.GetEncryptedBytes(key, encryptionKey)
+}
+
 func (r ReadOnly) GetNode(key string) (ipld.Node, error) {
 	return r.m.GetNode(key)
 }

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"
@@ -33,8 +34,14 @@ 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 +55,64 @@ 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) {
+	// TODO: handle uint overflow below
+
+	// some fast path
+	switch val := v.(type) {
+	case bool:
+		return basicnode.NewBool(val), nil
+	case string:
+		return basicnode.NewString(val), nil
+	case int:
+		return basicnode.NewInt(int64(val)), 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:
+		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:
+		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
@@ -90,10 +155,14 @@ 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:
@@ -106,6 +175,11 @@ func anyAssemble(val any) qp.Assemble {
 		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

@@ -3,7 +3,9 @@ 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"
 )
@@ -53,6 +55,7 @@ func TestMap(t *testing.T) {
 				"barbar": "foo",
 			},
 		},
+		"link": cid.MustParse("bafzbeigai3eoy2ccc7ybwjfz5r3rdxqrinwi4rwytly24tdbh6yk7zslrm"),
 	})
 	require.NoError(t, err)
 
@@ -115,6 +118,140 @@ 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")))
+
+	v, 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 must[T any](t T, err error) T {

pkg/policy/match.go

@@ -9,21 +9,19 @@ import (
 	"github.com/ipld/go-ipld-prime/must"
 )
 
-// MatchTrace, if set, will print tracing statements to stdout of the policy matching resolution.
-var MatchTrace = false
-
 // 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.
@@ -62,7 +60,7 @@ const (
 // - matchResultNoData: if the selector didn't match the expected data.
 // For matchResultTrue and matchResultNoData, the leaf-most (innermost) statement failing to be true is returned,
 // as well as the corresponding root-most encompassing statement.
-func matchStatement(cur Statement, node ipld.Node) (output matchResult, leafMost Statement) {
+func matchStatement(cur Statement, node ipld.Node) (_ matchResult, leafMost Statement) {
 	var boolToRes = func(v bool) (matchResult, Statement) {
 		if v {
 			return matchResultTrue, nil
@@ -70,11 +68,6 @@ func matchStatement(cur Statement, node ipld.Node) (output matchResult, leafMost
 			return matchResultFalse, cur
 		}
 	}
-	if MatchTrace {
-		defer func() {
-			fmt.Printf("match %v --> %v\n", cur, matchResToStr(output))
-		}()
-	}
 
 	switch cur.Kind() {
 	case KindEqual:
@@ -139,9 +132,9 @@ func matchStatement(cur Statement, node ipld.Node) (output matchResult, leafMost
 			case matchResultNoData, matchResultOptionalNoData:
 				return res, leaf
 			case matchResultTrue:
-				return matchResultFalse, leaf
+				return matchResultFalse, cur
 			case matchResultFalse:
-				return matchResultTrue, leaf
+				return matchResultTrue, nil
 			}
 		}
 	case KindAnd:
@@ -282,18 +275,3 @@ func gt(order int) bool  { return order == 1 }
 func gte(order int) bool { return order == 0 || order == 1 }
 func lt(order int) bool  { return order == -1 }
 func lte(order int) bool { return order == 0 || order == -1 }
-
-func matchResToStr(res matchResult) string {
-	switch res {
-	case matchResultTrue:
-		return "True"
-	case matchResultFalse:
-		return "False"
-	case matchResultNoData:
-		return "NoData"
-	case matchResultOptionalNoData:
-		return "OptionalNoData"
-	default:
-		panic("invalid matchResult")
-	}
-}

pkg/policy/match_test.go

@@ -7,8 +7,11 @@ import (
 	"github.com/ipfs/go-cid"
 	"github.com/ipld/go-ipld-prime"
 	"github.com/ipld/go-ipld-prime/codec/dagjson"
+	"github.com/ipld/go-ipld-prime/datamodel"
+	"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/stretchr/testify/assert"
 	"github.com/stretchr/testify/require"
 
 	"github.com/ucan-wg/go-ucan/pkg/policy/literal"
@@ -17,228 +20,252 @@ 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()
+			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()
+			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()
+			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) {
 			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()
+			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()
+			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("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("negation", func(t *testing.T) {
-		np := basicnode.Prototype.Bool
-		nb := np.NewBuilder()
-		nb.AssignBool(false)
-		nd := nb.Build()
+		nd := literal.Bool(false)
 
 		pol := MustConstruct(Not(Equal(".", literal.Bool(true))))
-		ok := pol.Match(nd)
+		ok, leaf := pol.Match(nd)
 		require.True(t, ok)
+		require.Nil(t, leaf)
 
 		pol = MustConstruct(Not(Equal(".", literal.Bool(false))))
-		ok = pol.Match(nd)
+		ok, leaf = pol.Match(nd)
 		require.False(t, ok)
+		require.Equal(t, pol[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 +273,9 @@ 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 +283,18 @@ 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 +302,9 @@ 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 +312,14 @@ 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 +333,12 @@ 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 +352,56 @@ 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 +419,8 @@ 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) {
@@ -509,7 +524,7 @@ func FuzzMatch(f *testing.F) {
 			t.Skip()
 		}
 
-		policy.Match(dataNode)
+		_, _ = policy.Match(dataNode)
 	})
 }
 
@@ -584,7 +599,7 @@ 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)
 		})
 	}
@@ -889,3 +904,55 @@ func TestPartialMatch(t *testing.T) {
 		})
 	}
 }
+
+// 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()
+
+	pol := MustConstruct(
+		Equal(".from", literal.String("alice@example.com")),
+		Any(".to", Like(".", "*@example.com")),
+	)
+
+	t.Run("with passing args", func(t *testing.T) {
+		t.Parallel()
+
+		argsNode, err := qp.BuildMap(basicnode.Prototype.Any, 2, func(ma datamodel.MapAssembler) {
+			qp.MapEntry(ma, "from", qp.String("alice@example.com"))
+			qp.MapEntry(ma, "to", qp.List(2, func(la datamodel.ListAssembler) {
+				qp.ListEntry(la, qp.String("bob@example.com"))
+				qp.ListEntry(la, qp.String("carol@not.example.com"))
+			}))
+			qp.MapEntry(ma, "title", qp.String("Coffee"))
+			qp.MapEntry(ma, "body", qp.String("Still on for coffee"))
+		})
+		require.NoError(t, err)
+
+		exec, stmt := pol.Match(argsNode)
+		assert.True(t, exec)
+		assert.Nil(t, stmt)
+	})
+
+	t.Run("fails on recipients (second statement)", func(t *testing.T) {
+		t.Parallel()
+
+		argsNode, err := qp.BuildMap(basicnode.Prototype.Any, 2, func(ma datamodel.MapAssembler) {
+			qp.MapEntry(ma, "from", qp.String("alice@example.com"))
+			qp.MapEntry(ma, "to", qp.List(2, func(la datamodel.ListAssembler) {
+				qp.ListEntry(la, qp.String("bob@null.com"))
+				qp.ListEntry(la, qp.String("carol@elsewhere.example.com"))
+			}))
+			qp.MapEntry(ma, "title", qp.String("Coffee"))
+			qp.MapEntry(ma, "body", qp.String("Still on for coffee"))
+		})
+		require.NoError(t, err)
+
+		exec, stmt := pol.Match(argsNode)
+		assert.False(t, exec)
+		assert.NotNil(t, stmt)
+	})
+}

pkg/policy/policy_test.go

@@ -37,6 +37,37 @@ func ExamplePolicy() {
 	// ]
 }
 
+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"]]]
+	//     ]
+	// ]
+}
+
 func TestConstruct(t *testing.T) {
 	pol, err := policy.Construct(
 		policy.Equal(".status", literal.String("draft")),

pkg/policy/selector/parsing_test.go

@@ -1,7 +1,6 @@
 package selector
 
 import (
-	"fmt"
 	"math"
 	"testing"
 
@@ -354,7 +353,6 @@ 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 +402,11 @@ 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) {
@@ -554,9 +550,3 @@ func TestParse(t *testing.T) {
 		require.Error(t, err)
 	})
 }
-
-func printSegments(s Selector) {
-	for i, seg := range s {
-		fmt.Printf("%d: %s\n", i, seg.String())
-	}
-}

pkg/policy/selector/selector_test.go

@@ -2,7 +2,6 @@ package selector
 
 import (
 	"errors"
-	"fmt"
 	"strings"
 	"testing"
 
@@ -13,7 +12,6 @@ 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 +85,6 @@ 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 +97,6 @@ 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 +104,6 @@ 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 +116,6 @@ 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)
 
@@ -142,8 +132,6 @@ 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")
 	})
 
@@ -164,8 +152,6 @@ 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)
 

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()
 

token/delegation/delegation.go

@@ -10,17 +10,16 @@ package delegation
 // TODO: change the "delegation" link above when the specification is merged
 
 import (
-	"crypto/rand"
 	"errors"
 	"fmt"
 	"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.
@@ -47,15 +46,10 @@ type Token struct {
 
 // New creates a validated Token from the provided parameters and options.
 //
-// When creating a delegated token, the Issuer's (iss) DID is assembed
+// When creating a delegated token, the Issuer's (iss) DID is assembled
 // 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
-	}
-
+func New(iss, aud did.DID, cmd command.Command, pol policy.Policy, opts ...Option) (*Token, error) {
 	tkn := &Token{
 		issuer:   iss,
 		audience: aud,
@@ -72,8 +66,9 @@ 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
 		}
@@ -92,15 +87,10 @@ func New(privKey crypto.PrivKey, aud did.DID, cmd command.Command, pol policy.Po
 // 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
-	}
+func Root(iss, aud did.DID, cmd command.Command, pol policy.Policy, opts ...Option) (*Token, error) {
+	opts = append(opts, WithSubject(iss))
 
-	opts = append(opts, WithSubject(sub))
-
-	return New(privKey, aud, cmd, pol, opts...)
+	return New(iss, aud, cmd, pol, opts...)
 }
 
 // Issuer returns the did.DID representing the Token's issuer.
@@ -152,6 +142,24 @@ func (t *Token) Expiration() *time.Time {
 	return t.expiration
 }
 
+// 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) validate() error {
 	var errs error
 
@@ -184,27 +192,19 @@ 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)
 	}
 
@@ -215,15 +215,8 @@ func tokenFromModel(m tokenPayloadModel) (*Token, error) {
 
 	tkn.meta = m.Meta
 
-	if m.Nbf != nil {
-		t := time.Unix(*m.Nbf, 0)
-		tkn.notBefore = &t
-	}
-
-	if m.Exp != nil {
-		t := time.Unix(*m.Exp, 0)
-		tkn.expiration = &t
-	}
+	tkn.notBefore = parse.OptionalTimestamp(m.Nbf)
+	tkn.expiration = parse.OptionalTimestamp(m.Exp)
 
 	if err := tkn.validate(); err != nil {
 		return nil, err
@@ -231,14 +224,3 @@ 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"
@@ -17,16 +17,8 @@ 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 = `
 [
 	[
 		"==",
@@ -64,20 +56,15 @@ const (
 ]
 `
 
-	newCID  = "zdpuAn9JgGPvnt2WCmTaKktZdbuvcVGTg9bUT5kQaufwUtZ6e"
+	newCID  = "zdpuAwa4qv3ncMDPeDoqVxjZy3JoyWsbqUzm94rdA1AvRFkkw"
 	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)
 
@@ -88,27 +75,25 @@ 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,
 			delegation.WithNonce([]byte(nonce)),
-			delegation.WithSubject(sub),
+			delegation.WithSubject(didtest.PersonaAlice.DID()),
 			delegation.WithExpiration(exp),
 			delegation.WithMeta("foo", "fooo"),
 			delegation.WithMeta("bar", "barr"),
 		)
 		require.NoError(t, err)
 
-		data, err := tkn.ToDagJson(privKey)
+		data, err := tkn.ToDagJson(didtest.PersonaAlice.PrivKey())
 		require.NoError(t, err)
 
-		t.Log(string(data))
-
 		golden.Assert(t, string(data), "new.dagjson")
 	})
 
 	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 +101,109 @@ func TestConstructors(t *testing.T) {
 		)
 		require.NoError(t, err)
 
-		data, err := tkn.ToDagJson(privKey)
+		data, err := tkn.ToDagJson(didtest.PersonaAlice.PrivKey())
 		require.NoError(t, err)
 
-		t.Log(string(data))
-
 		golden.Assert(t, string(data), "root.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.New(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.New(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 +1,234 @@
+package main
+
+import (
+	"os"
+	"path/filepath"
+	"slices"
+	"time"
+
+	"github.com/dave/jennifer/jen"
+	"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/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
+	aud     did.DID
+	sub     did.DID
+	cmd     command.Command
+	pol     policy.Policy
+	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:     policy.Policy{},
+		opts: []delegation.Option{
+			delegation.WithSubject(didtest.PersonaAlice.DID()),
+			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.opts = append(p.opts, delegation.WithSubject(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))
+			}},
+		}
+
+		// 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.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 {
+	file := jen.NewFile("delegationtest")
+	file.HeaderComment("Code generated by delegationtest - DO NOT EDIT.")
+
+	refs := map[cid.Cid]string{}
+
+	for _, d := range g.dlgs {
+		refs[d.id] = d.name + "CID"
+
+		file.Var().Defs(
+			jen.Id(d.name+"CID").Op("=").Qual("github.com/ipfs/go-cid", "MustParse").Call(jen.Lit(d.id.String())),
+			jen.Id(d.name).Op("=").Id("mustGetDelegation").Call(jen.Id(d.name+"CID")),
+		)
+		file.Line()
+	}
+
+	for _, c := range g.chains {
+		g := jen.CustomFunc(jen.Options{
+			Multi:     true,
+			Separator: ",",
+			Close:     "\n",
+		}, func(g *jen.Group) {
+			slices.Reverse(c.prf)
+			for _, p := range c.prf {
+				g.Id(refs[p])
+			}
+		})
+
+		file.Var().Id(c.name).Op("=").Index().Qual("github.com/ipfs/go-cid", "Cid").Values(g)
+		file.Line()
+	}
+
+	return file.Save("../token_gen.go")
+}

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 +1,112 @@
+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 {
+	tokens map[cid.Cid]*delegation.Token
+}
+
+var (
+	once sync.Once
+	ldr  delegation.Loader
+)
+
+// GetDelegationLoader returns a singleton instance of a test
+// DelegationLoader containing all the tokens present in the data/
+// directory.
+func GetDelegationLoader() delegation.Loader {
+	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) {
+	tkn, ok := l.tokens[id]
+	if !ok {
+		return nil, delegation.ErrDelegationNotFound
+	}
+
+	return tkn, nil
+}
+
+func loadDelegations() (delegation.Loader, error) {
+	dirEntries, err := fs.ReadDir(TokenDir)
+	if err != nil {
+		return nil, err
+	}
+
+	tkns := make(map[cid.Cid]*delegation.Token, 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
+		}
+
+		tkns[id] = tkn
+	}
+
+	return &delegationLoader{
+		tokens: tkns,
+	}, 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 mustGetDelegation(id cid.Cid) *delegation.Token {
+	tkn, err := GetDelegation(id)
+	if err != nil {
+		panic(err)
+	}
+	return tkn
+}

token/delegation/delegationtest/token_gen.go

@@ -0,0 +1,240 @@
+// Code generated by delegationtest - DO NOT EDIT.
+
+package delegationtest
+
+import gocid "github.com/ipfs/go-cid"
+
+var (
+	TokenAliceBobCID = gocid.MustParse("bafyreicidrwvmac5lvjypucgityrtjsknojraio7ujjli4r5eyby66wjzm")
+	TokenAliceBob    = mustGetDelegation(TokenAliceBobCID)
+)
+
+var (
+	TokenBobCarolCID = gocid.MustParse("bafyreihxv2uhq43oxllzs2xfvxst7wtvvvl7pohb2chcz6hjvfv2ntea5u")
+	TokenBobCarol    = mustGetDelegation(TokenBobCarolCID)
+)
+
+var (
+	TokenCarolDanCID = gocid.MustParse("bafyreihclsgiroazq3heqdswvj2cafwqbpboicq7immo65scl7ahktpsdq")
+	TokenCarolDan    = mustGetDelegation(TokenCarolDanCID)
+)
+
+var (
+	TokenDanErinCID = gocid.MustParse("bafyreicja6ihewy64p3ake56xukotafjlkh4uqep2qhj52en46zzfwby3e")
+	TokenDanErin    = mustGetDelegation(TokenDanErinCID)
+)
+
+var (
+	TokenErinFrankCID = gocid.MustParse("bafyreicjlx3lobxm6hl5s4htd4ydwkkqeiou6rft4rnvulfdyoew565vka")
+	TokenErinFrank    = mustGetDelegation(TokenErinFrankCID)
+)
+
+var (
+	TokenCarolDan_InvalidExpandedCommandCID = gocid.MustParse("bafyreid3m3pk53gqgp5rlzqhvpedbwsqbidqlp4yz64vknwbzj7bxrmsr4")
+	TokenCarolDan_InvalidExpandedCommand    = mustGetDelegation(TokenCarolDan_InvalidExpandedCommandCID)
+)
+
+var (
+	TokenDanErin_InvalidExpandedCommandCID = gocid.MustParse("bafyreifn4sy5onwajx3kqvot5mib6m6xarzrqjozqbzgmzpmc5ox3g2uzm")
+	TokenDanErin_InvalidExpandedCommand    = mustGetDelegation(TokenDanErin_InvalidExpandedCommandCID)
+)
+
+var (
+	TokenErinFrank_InvalidExpandedCommandCID = gocid.MustParse("bafyreidmpgd36jznmq42bs34o4qi3fcbrsh4idkg6ejahudejzwb76fwxe")
+	TokenErinFrank_InvalidExpandedCommand    = mustGetDelegation(TokenErinFrank_InvalidExpandedCommandCID)
+)
+
+var (
+	TokenCarolDan_ValidAttenuatedCommandCID = gocid.MustParse("bafyreiekhtm237vyapk3c6voeb5lnz54crebqdqi3x4wn4u4cbrrhzsqfe")
+	TokenCarolDan_ValidAttenuatedCommand    = mustGetDelegation(TokenCarolDan_ValidAttenuatedCommandCID)
+)
+
+var (
+	TokenDanErin_ValidAttenuatedCommandCID = gocid.MustParse("bafyreicrvzqferyy7rgo75l5rn6r2nl7zyeexxjmu3dm4ff7rn2coblj4y")
+	TokenDanErin_ValidAttenuatedCommand    = mustGetDelegation(TokenDanErin_ValidAttenuatedCommandCID)
+)
+
+var (
+	TokenErinFrank_ValidAttenuatedCommandCID = gocid.MustParse("bafyreie6fhspk53kplcc2phla3e7z7fzldlbmmpuwk6nbow5q6s2zjmw2q")
+	TokenErinFrank_ValidAttenuatedCommand    = mustGetDelegation(TokenErinFrank_ValidAttenuatedCommandCID)
+)
+
+var (
+	TokenCarolDan_InvalidSubjectCID = gocid.MustParse("bafyreifgksz6756if42tnc6rqsnbaa2u3fdrveo7ek44lnj2d64d5sw26u")
+	TokenCarolDan_InvalidSubject    = mustGetDelegation(TokenCarolDan_InvalidSubjectCID)
+)
+
+var (
+	TokenDanErin_InvalidSubjectCID = gocid.MustParse("bafyreibdwew5nypsxrm4fq73wu6hw3lgwwiolj3bi33xdrbgcf3ogm6fty")
+	TokenDanErin_InvalidSubject    = mustGetDelegation(TokenDanErin_InvalidSubjectCID)
+)
+
+var (
+	TokenErinFrank_InvalidSubjectCID = gocid.MustParse("bafyreicr364mj3n7x4iyhcksxypelktcqkkw3ptg7ggxtqegw3p3mr6zc4")
+	TokenErinFrank_InvalidSubject    = mustGetDelegation(TokenErinFrank_InvalidSubjectCID)
+)
+
+var (
+	TokenCarolDan_InvalidExpiredCID = gocid.MustParse("bafyreigenypixaxvhzlry5rjnywvjyl4xvzlzxz2ui74uzys7qdhos4bbu")
+	TokenCarolDan_InvalidExpired    = mustGetDelegation(TokenCarolDan_InvalidExpiredCID)
+)
+
+var (
+	TokenDanErin_InvalidExpiredCID = gocid.MustParse("bafyreifvnfb7zqocpdysedcvjkb4y7tqfuziuqjhbbdoay4zg33pwpbzqi")
+	TokenDanErin_InvalidExpired    = mustGetDelegation(TokenDanErin_InvalidExpiredCID)
+)
+
+var (
+	TokenErinFrank_InvalidExpiredCID = gocid.MustParse("bafyreicvydzt3obkqx7krmoi3zu4tlirlksibxfks5jc7vlvjxjamv2764")
+	TokenErinFrank_InvalidExpired    = mustGetDelegation(TokenErinFrank_InvalidExpiredCID)
+)
+
+var (
+	TokenCarolDan_InvalidInactiveCID = gocid.MustParse("bafyreicea5y2nvlitvxijkupeavtg23i7ktjk3uejnaquguurzptiabk4u")
+	TokenCarolDan_InvalidInactive    = mustGetDelegation(TokenCarolDan_InvalidInactiveCID)
+)
+
+var (
+	TokenDanErin_InvalidInactiveCID = gocid.MustParse("bafyreifsgqzkmxj2vexuts3z766mwcjreiisjg2jykyzf7tbj5sclutpvq")
+	TokenDanErin_InvalidInactive    = mustGetDelegation(TokenDanErin_InvalidInactiveCID)
+)
+
+var (
+	TokenErinFrank_InvalidInactiveCID = gocid.MustParse("bafyreifbfegon24c6dndiqyktahzs65vhyasrygbw7nhsvojn6distsdre")
+	TokenErinFrank_InvalidInactive    = mustGetDelegation(TokenErinFrank_InvalidInactiveCID)
+)
+
+var ProofAliceBob = []gocid.Cid{
+	TokenAliceBobCID,
+}
+
+var ProofAliceBobCarol = []gocid.Cid{
+	TokenBobCarolCID,
+	TokenAliceBobCID,
+}
+
+var ProofAliceBobCarolDan = []gocid.Cid{
+	TokenCarolDanCID,
+	TokenBobCarolCID,
+	TokenAliceBobCID,
+}
+
+var ProofAliceBobCarolDanErin = []gocid.Cid{
+	TokenDanErinCID,
+	TokenCarolDanCID,
+	TokenBobCarolCID,
+	TokenAliceBobCID,
+}
+
+var ProofAliceBobCarolDanErinFrank = []gocid.Cid{
+	TokenErinFrankCID,
+	TokenDanErinCID,
+	TokenCarolDanCID,
+	TokenBobCarolCID,
+	TokenAliceBobCID,
+}
+
+var ProofAliceBobCarolDan_InvalidExpandedCommand = []gocid.Cid{
+	TokenCarolDan_InvalidExpandedCommandCID,
+	TokenBobCarolCID,
+	TokenAliceBobCID,
+}
+
+var ProofAliceBobCarolDanErin_InvalidExpandedCommand = []gocid.Cid{
+	TokenDanErin_InvalidExpandedCommandCID,
+	TokenCarolDan_InvalidExpandedCommandCID,
+	TokenBobCarolCID,
+	TokenAliceBobCID,
+}
+
+var ProofAliceBobCarolDanErinFrank_InvalidExpandedCommand = []gocid.Cid{
+	TokenErinFrank_InvalidExpandedCommandCID,
+	TokenDanErin_InvalidExpandedCommandCID,
+	TokenCarolDan_InvalidExpandedCommandCID,
+	TokenBobCarolCID,
+	TokenAliceBobCID,
+}
+
+var ProofAliceBobCarolDan_ValidAttenuatedCommand = []gocid.Cid{
+	TokenCarolDan_ValidAttenuatedCommandCID,
+	TokenBobCarolCID,
+	TokenAliceBobCID,
+}
+
+var ProofAliceBobCarolDanErin_ValidAttenuatedCommand = []gocid.Cid{
+	TokenDanErin_ValidAttenuatedCommandCID,
+	TokenCarolDan_ValidAttenuatedCommandCID,
+	TokenBobCarolCID,
+	TokenAliceBobCID,
+}
+
+var ProofAliceBobCarolDanErinFrank_ValidAttenuatedCommand = []gocid.Cid{
+	TokenErinFrank_ValidAttenuatedCommandCID,
+	TokenDanErin_ValidAttenuatedCommandCID,
+	TokenCarolDan_ValidAttenuatedCommandCID,
+	TokenBobCarolCID,
+	TokenAliceBobCID,
+}
+
+var ProofAliceBobCarolDan_InvalidSubject = []gocid.Cid{
+	TokenCarolDan_InvalidSubjectCID,
+	TokenBobCarolCID,
+	TokenAliceBobCID,
+}
+
+var ProofAliceBobCarolDanErin_InvalidSubject = []gocid.Cid{
+	TokenDanErin_InvalidSubjectCID,
+	TokenCarolDan_InvalidSubjectCID,
+	TokenBobCarolCID,
+	TokenAliceBobCID,
+}
+
+var ProofAliceBobCarolDanErinFrank_InvalidSubject = []gocid.Cid{
+	TokenErinFrank_InvalidSubjectCID,
+	TokenDanErin_InvalidSubjectCID,
+	TokenCarolDan_InvalidSubjectCID,
+	TokenBobCarolCID,
+	TokenAliceBobCID,
+}
+
+var ProofAliceBobCarolDan_InvalidExpired = []gocid.Cid{
+	TokenCarolDan_InvalidExpiredCID,
+	TokenBobCarolCID,
+	TokenAliceBobCID,
+}
+
+var ProofAliceBobCarolDanErin_InvalidExpired = []gocid.Cid{
+	TokenDanErin_InvalidExpiredCID,
+	TokenCarolDan_InvalidExpiredCID,
+	TokenBobCarolCID,
+	TokenAliceBobCID,
+}
+
+var ProofAliceBobCarolDanErinFrank_InvalidExpired = []gocid.Cid{
+	TokenErinFrank_InvalidExpiredCID,
+	TokenDanErin_InvalidExpiredCID,
+	TokenCarolDan_InvalidExpiredCID,
+	TokenBobCarolCID,
+	TokenAliceBobCID,
+}
+
+var ProofAliceBobCarolDan_InvalidInactive = []gocid.Cid{
+	TokenCarolDan_InvalidInactiveCID,
+	TokenBobCarolCID,
+	TokenAliceBobCID,
+}
+
+var ProofAliceBobCarolDanErin_InvalidInactive = []gocid.Cid{
+	TokenDanErin_InvalidInactiveCID,
+	TokenCarolDan_InvalidInactiveCID,
+	TokenBobCarolCID,
+	TokenAliceBobCID,
+}
+
+var ProofAliceBobCarolDanErinFrank_InvalidInactive = []gocid.Cid{
+	TokenErinFrank_InvalidInactiveCID,
+	TokenDanErin_InvalidInactiveCID,
+	TokenCarolDan_InvalidInactiveCID,
+	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 +41,8 @@ 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,
+		delegation.WithSubject(didtest.PersonaAlice.DID()),
 		delegation.WithExpirationIn(time.Hour),
 		delegation.WithNotBeforeIn(time.Minute),
 		delegation.WithMeta("foo", "bar"),
@@ -61,101 +51,91 @@ 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 +151,7 @@ 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 +160,7 @@ 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 +169,82 @@ 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)

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/loader.go

@@ -0,0 +1,17 @@
+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)
+}

token/delegation/options.go

@@ -44,6 +44,22 @@ 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 aesKey.
+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 aesKey.
+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 {

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()
@@ -36,18 +36,13 @@ func TestSchemaRoundTrip(t *testing.T) {
 		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))
 
 		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))
 	})
@@ -65,7 +60,6 @@ func TestSchemaRoundTrip(t *testing.T) {
 
 		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))
 
@@ -79,6 +73,16 @@ 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 +94,7 @@ 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":"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/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/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 {

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 +1,22 @@
+package parse
+
+import (
+	"time"
+
+	"github.com/ucan-wg/go-ucan/did"
+)
+
+func OptionalDID(s *string) (did.DID, error) {
+	if s == nil {
+		return did.Undef, nil
+	}
+	return did.Parse(*s)
+}
+
+func OptionalTimestamp(sec *int64) *time.Time {
+	if sec == nil {
+		return nil
+	}
+	t := time.Unix(*sec, 0)
+	return &t
+}

token/invocation/errors.go

@@ -0,0 +1,37 @@
+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")
+)

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, sub, cmd, 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
+}

token/invocation/invocation.go

@@ -8,37 +8,132 @@
 package invocation
 
 import (
-	"crypto/rand"
 	"errors"
 	"fmt"
 	"time"
 
+	"github.com/ipfs/go-cid"
+
 	"github.com/ucan-wg/go-ucan/did"
+	"github.com/ucan-wg/go-ucan/pkg/args"
 	"github.com/ucan-wg/go-ucan/pkg/command"
 	"github.com/ucan-wg/go-ucan/pkg/meta"
+	"github.com/ucan-wg/go-ucan/token/delegation"
+	"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 invocation.
 type Token struct {
-	// Issuer DID (invoker)
+	// The DID of the Invoker
 	issuer did.DID
-	// Audience DID (receiver/executor)
-	audience did.DID
-	// Subject DID (subject being invoked)
+	// The DID of Subject being invoked
 	subject did.DID
-	// The Command to invoke
+	// The DID of the intended Executor if different from the Subject
+	audience did.DID
+
+	// The Command
 	command command.Command
-	// TODO: args
-	// TODO: prf
-	// A unique, random nonce
-	nonce []byte
+	// The Command's arguments
+	arguments *args.Args
+	// CIDs of the delegation.Token that prove the chain of authority
+	// They need to form a strictly linear chain, and being ordered starting from the
+	// leaf Delegation (with aud matching the invocation's iss), in a strict sequence
+	// where the iss of the previous Delegation matches the aud of the next Delegation.
+	proof []cid.Cid
 	// Arbitrary Metadata
 	meta *meta.Meta
+
+	// A unique, random nonce
+	nonce []byte
 	// The timestamp at which the Invocation becomes invalid
 	expiration *time.Time
 	// The timestamp at which the Invocation was created
 	invokedAt *time.Time
-	// TODO: cause
+
+	// An optional CID of the Receipt that enqueued the Task
+	cause *cid.Cid
+}
+
+// New creates an invocation Token with the provided options.
+//
+// If no nonce is provided, a random 12-byte nonce is generated. Use the
+// WithNonce or WithEmptyNonce options to specify provide your own nonce
+// or to leave the nonce empty respectively.
+//
+// If no invokedAt is provided, the current time is used. Use the
+// WithInvokedAt or WithInvokedAtIn Options to specify a different time
+// or the WithoutInvokedAt Option to clear the Token's invokedAt field.
+//
+// With the exception of the WithMeta option, all others will overwrite
+// the previous contents of their target field.
+func New(iss, sub did.DID, cmd command.Command, prf []cid.Cid, opts ...Option) (*Token, error) {
+	iat := time.Now()
+
+	tkn := Token{
+		issuer:    iss,
+		subject:   sub,
+		command:   cmd,
+		arguments: args.New(),
+		proof:     prf,
+		meta:      meta.NewMeta(),
+		nonce:     nil,
+		invokedAt: &iat,
+	}
+
+	for _, opt := range opts {
+		if err := opt(&tkn); err != nil {
+			return nil, err
+		}
+	}
+
+	var err error
+	if len(tkn.nonce) == 0 {
+		tkn.nonce, err = nonce.Generate()
+		if err != nil {
+			return nil, err
+		}
+	}
+
+	if err := tkn.validate(); err != nil {
+		return nil, err
+	}
+
+	return &tkn, nil
+}
+
+func (t *Token) ExecutionAllowed(loader delegation.Loader) error {
+	return t.executionAllowed(loader, t.arguments)
+}
+
+func (t *Token) ExecutionAllowedWithArgsHook(loader delegation.Loader, hook func(args args.ReadOnly) (*args.Args, error)) error {
+	newArgs, err := hook(t.arguments.ReadOnly())
+	if err != nil {
+		return err
+	}
+	return t.executionAllowed(loader, newArgs)
+}
+
+func (t *Token) executionAllowed(loader delegation.Loader, arguments *args.Args) error {
+	delegations, err := t.loadProofs(loader)
+	if err != nil {
+		// All referenced delegations must be available - 4b
+		return err
+	}
+
+	if err := t.verifyProofs(delegations); err != nil {
+		return err
+	}
+
+	if err := t.verifyTimeBound(delegations); err != nil {
+		return err
+	}
+
+	if err := t.verifyArgs(delegations, arguments); err != nil {
+		return err
+	}
+
+	return nil
 }
 
 // Issuer returns the did.DID representing the Token's issuer.
@@ -46,28 +141,31 @@ func (t *Token) Issuer() did.DID {
 	return t.issuer
 }
 
+// Subject returns the did.DID representing the Token's subject.
+func (t *Token) Subject() did.DID {
+	return t.subject
+}
+
 // Audience returns the did.DID representing the Token's audience.
 func (t *Token) Audience() did.DID {
 	return t.audience
 }
 
-// Subject returns the did.DID representing the Token's subject.
-//
-// This field may be did.Undef for delegations that are [Powerlined] but
-// must be equal to the value returned by the Issuer method for root
-// tokens.
-func (t *Token) Subject() did.DID {
-	return t.subject
-}
-
 // Command returns the capability's command.Command.
 func (t *Token) Command() command.Command {
 	return t.command
 }
 
-// Nonce returns the random Nonce encapsulated in this Token.
-func (t *Token) Nonce() []byte {
-	return t.nonce
+// Arguments returns the arguments to be used when the command is
+// invoked.
+func (t *Token) Arguments() args.ReadOnly {
+	return t.arguments.ReadOnly()
+}
+
+// Proof() returns the ordered list of cid.Cid which reference the
+// delegation Tokens that authorize this invocation.
+func (t *Token) Proof() []cid.Cid {
+	return t.proof
 }
 
 // Meta returns the Token's metadata.
@@ -75,11 +173,43 @@ func (t *Token) Meta() meta.ReadOnly {
 	return t.meta.ReadOnly()
 }
 
+// Nonce returns the random Nonce encapsulated in this Token.
+func (t *Token) Nonce() []byte {
+	return t.nonce
+}
+
 // Expiration returns the time at which the Token expires.
 func (t *Token) Expiration() *time.Time {
 	return t.expiration
 }
 
+// InvokedAt returns the time.Time at which the invocation token was
+// created.
+func (t *Token) InvokedAt() *time.Time {
+	return t.invokedAt
+}
+
+// Cause returns the Token's (optional) cause field which may specify
+// which describes the Receipt that requested the invocation.
+func (t *Token) Cause() *cid.Cid {
+	return t.cause
+}
+
+// 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
+	}
+	return true
+}
+
 func (t *Token) validate() error {
 	var errs error
 
@@ -90,8 +220,7 @@ func (t *Token) validate() error {
 	}
 
 	requiredDID(t.issuer, "Issuer")
-
-	// TODO
+	requiredDID(t.subject, "Subject")
 
 	if len(t.nonce) < 12 {
 		errs = errors.Join(errs, fmt.Errorf("token nonce too small"))
@@ -100,25 +229,58 @@ func (t *Token) validate() error {
 	return errs
 }
 
+func (t *Token) loadProofs(loader delegation.Loader) (res []*delegation.Token, err error) {
+	res = make([]*delegation.Token, len(t.proof))
+	for i, c := range t.proof {
+		res[i], err = loader.GetDelegation(c)
+		if err != nil {
+			return nil, fmt.Errorf("%w: need %s", ErrMissingDelegation, c)
+		}
+	}
+	return res, nil
+}
+
 // tokenFromModel build a decoded view of the raw IPLD data.
 // This function also serves as validation.
 func tokenFromModel(m tokenPayloadModel) (*Token, error) {
 	var (
 		tkn Token
+		err error
 	)
 
-	// TODO
+	if tkn.issuer, err = did.Parse(m.Iss); err != nil {
+		return nil, fmt.Errorf("parse iss: %w", err)
+	}
+
+	if tkn.subject, err = did.Parse(m.Sub); err != nil {
+		return nil, fmt.Errorf("parse subject: %w", err)
+	}
+
+	if tkn.audience, err = parse.OptionalDID(m.Aud); err != nil {
+		return nil, fmt.Errorf("parse audience: %w", err)
+	}
+
+	if tkn.command, err = command.Parse(m.Cmd); err != nil {
+		return nil, fmt.Errorf("parse command: %w", err)
+	}
+
+	if len(m.Nonce) == 0 {
+		return nil, fmt.Errorf("nonce is required")
+	}
+	tkn.nonce = m.Nonce
+
+	tkn.arguments = m.Args
+	tkn.proof = m.Prf
+	tkn.meta = m.Meta
+
+	tkn.expiration = parse.OptionalTimestamp(m.Exp)
+	tkn.invokedAt = parse.OptionalTimestamp(m.Iat)
+
+	tkn.cause = m.Cause
+
+	if err := tkn.validate(); err != nil {
+		return nil, err
+	}
 
 	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/invocation/invocation.ipldsch

@@ -1,23 +1,32 @@
+
 type DID string
 
 # The Invocation Payload attaches sender, receiver, and provenance to the Task.
 type Payload struct {
-    # Issuer DID (sender)
+    # The DID of the invoker
     iss DID
-    # Audience DID (receiver)
-    aud DID
-    # Principal that the chain is about (the Subject)
-    sub optional DID
+    # The Subject being invoked
+    sub DID
+    # The DID of the intended Executor if different from the Subject
+    aud optional DID
 
-    # The Command to eventually invoke
+    # The Command
     cmd String
-
-    # A unique, random nonce
-    nonce Bytes
+    # The Command's Arguments
+    args { String : Any}
+    # Delegations that prove the chain of authority
+    prf [ Link ]
 
     # Arbitrary Metadata
-    meta {String : Any}
+    meta optional { String : Any }
 
+    # A unique, random nonce
+    nonce optional Bytes
     # The timestamp at which the Invocation becomes invalid
     exp nullable Int
+    # The Timestamp at which the Invocation was created
+    iat optional Int
+
+    # An optional CID of the Receipt that enqueued the Task
+    cause optional Link
 }

token/invocation/invocation_test.go

@@ -0,0 +1,139 @@
+package invocation_test
+
+import (
+	"testing"
+
+	"github.com/ipfs/go-cid"
+	"github.com/stretchr/testify/require"
+
+	"github.com/ucan-wg/go-ucan/did/didtest"
+	"github.com/ucan-wg/go-ucan/pkg/args"
+	"github.com/ucan-wg/go-ucan/pkg/command"
+	"github.com/ucan-wg/go-ucan/token/delegation/delegationtest"
+	"github.com/ucan-wg/go-ucan/token/invocation"
+)
+
+const (
+	missingPrivKeyCfg = "CAESQMjRvrEIjpPYRQKmkAGw/pV0XgE958rYa4vlnKJjl1zz/sdnGnyV1xKLJk8D39edyjhHWyqcpgFnozQK62SG16k="
+	missingTknCIDStr  = "bafyreigwypmw6eul6vadi6g6lnfbsfo2zck7gfzsbjoroqs3djhnzzc7mm"
+	missingDIDStr     = "did:key:z6MkwboxFsH3kEuehBZ5fLkRmxi68yv1u38swA4r9Jm2VRma"
+)
+
+var emptyArguments = args.New()
+
+func TestToken_ExecutionAllowed(t *testing.T) {
+	t.Parallel()
+
+	t.Run("passes - only root", func(t *testing.T) {
+		t.Parallel()
+
+		testPasses(t, didtest.PersonaBob, delegationtest.NominalCommand, emptyArguments, delegationtest.ProofAliceBob)
+	})
+
+	t.Run("passes - valid chain", func(t *testing.T) {
+		t.Parallel()
+
+		testPasses(t, didtest.PersonaFrank, delegationtest.NominalCommand, emptyArguments, delegationtest.ProofAliceBobCarolDanErinFrank)
+	})
+
+	t.Run("passes - proof chain attenuates command", func(t *testing.T) {
+		t.Parallel()
+
+		testPasses(t, didtest.PersonaFrank, delegationtest.AttenuatedCommand, emptyArguments, delegationtest.ProofAliceBobCarolDanErinFrank_ValidAttenuatedCommand)
+	})
+
+	t.Run("passes - invocation attenuates command", func(t *testing.T) {
+		t.Parallel()
+
+		testPasses(t, didtest.PersonaFrank, delegationtest.AttenuatedCommand, emptyArguments, delegationtest.ProofAliceBobCarolDanErinFrank)
+	})
+
+	t.Run("fails - no proof", func(t *testing.T) {
+		t.Parallel()
+
+		testFails(t, invocation.ErrNoProof, didtest.PersonaCarol, delegationtest.NominalCommand, emptyArguments, delegationtest.ProofEmpty)
+	})
+
+	t.Run("fails - missing referenced delegation", func(t *testing.T) {
+		t.Parallel()
+
+		missingTknCID, err := cid.Parse(missingTknCIDStr)
+		require.NoError(t, err)
+
+		prf := []cid.Cid{missingTknCID, delegationtest.TokenAliceBobCID}
+		testFails(t, invocation.ErrMissingDelegation, didtest.PersonaCarol, delegationtest.NominalCommand, emptyArguments, prf)
+	})
+
+	t.Run("fails - referenced delegation expired", func(t *testing.T) {
+		t.Parallel()
+
+		testFails(t, invocation.ErrTokenInvalidNow, didtest.PersonaFrank, delegationtest.NominalCommand, emptyArguments, delegationtest.ProofAliceBobCarolDanErinFrank_InvalidExpired)
+
+	})
+
+	t.Run("fails - referenced delegation inactive", func(t *testing.T) {
+		t.Parallel()
+
+		testFails(t, invocation.ErrTokenInvalidNow, didtest.PersonaFrank, delegationtest.NominalCommand, emptyArguments, delegationtest.ProofAliceBobCarolDanErinFrank_InvalidInactive)
+	})
+
+	t.Run("fails - last (or only) delegation not root", func(t *testing.T) {
+		t.Parallel()
+
+		prf := []cid.Cid{delegationtest.TokenErinFrankCID, delegationtest.TokenDanErinCID, delegationtest.TokenCarolDanCID}
+		testFails(t, invocation.ErrLastNotRoot, didtest.PersonaFrank, delegationtest.NominalCommand, emptyArguments, prf)
+	})
+
+	t.Run("fails - broken chain", func(t *testing.T) {
+		t.Parallel()
+
+		prf := []cid.Cid{delegationtest.TokenCarolDanCID, delegationtest.TokenAliceBobCID}
+		testFails(t, invocation.ErrBrokenChain, didtest.PersonaFrank, delegationtest.NominalCommand, emptyArguments, prf)
+	})
+
+	t.Run("fails - first not issued to invoker", func(t *testing.T) {
+		t.Parallel()
+
+		prf := []cid.Cid{delegationtest.TokenBobCarolCID, delegationtest.TokenAliceBobCID}
+		testFails(t, invocation.ErrBrokenChain, didtest.PersonaFrank, delegationtest.NominalCommand, emptyArguments, prf)
+	})
+
+	t.Run("fails - proof chain expands command", func(t *testing.T) {
+		t.Parallel()
+
+		testFails(t, invocation.ErrCommandNotCovered, didtest.PersonaFrank, delegationtest.NominalCommand, emptyArguments, delegationtest.ProofAliceBobCarolDanErinFrank_InvalidExpandedCommand)
+	})
+
+	t.Run("fails - invocation expands command", func(t *testing.T) {
+		t.Parallel()
+
+		testFails(t, invocation.ErrCommandNotCovered, didtest.PersonaFrank, delegationtest.ExpandedCommand, emptyArguments, delegationtest.ProofAliceBobCarolDanErinFrank)
+	})
+
+	t.Run("fails - inconsistent subject", func(t *testing.T) {
+		t.Parallel()
+
+		testFails(t, invocation.ErrWrongSub, didtest.PersonaFrank, delegationtest.ExpandedCommand, emptyArguments, delegationtest.ProofAliceBobCarolDanErinFrank_InvalidSubject)
+	})
+}
+
+func test(t *testing.T, persona didtest.Persona, cmd command.Command, args *args.Args, prf []cid.Cid, opts ...invocation.Option) error {
+	t.Helper()
+
+	// TODO: use the args and add minimal test to check that they are verified against the policy
+
+	tkn, err := invocation.New(persona.DID(), didtest.PersonaAlice.DID(), cmd, prf, opts...)
+	require.NoError(t, err)
+
+	return tkn.ExecutionAllowed(delegationtest.GetDelegationLoader())
+}
+
+func testFails(t *testing.T, expErr error, persona didtest.Persona, cmd command.Command, args *args.Args, prf []cid.Cid, opts ...invocation.Option) {
+	err := test(t, persona, cmd, args, prf, opts...)
+	require.ErrorIs(t, err, expErr)
+}
+
+func testPasses(t *testing.T, persona didtest.Persona, cmd command.Command, args *args.Args, prf []cid.Cid, opts ...invocation.Option) {
+	err := test(t, persona, cmd, args, prf, opts...)
+	require.NoError(t, err)
+}

token/invocation/ipld.go

@@ -1,6 +1,7 @@
 package invocation
 
 import (
+	"fmt"
 	"io"
 
 	"github.com/ipfs/go-cid"
@@ -193,14 +194,21 @@ func FromIPLD(node datamodel.Node) (*Token, error) {
 }
 
 func (t *Token) toIPLD(privKey crypto.PrivKey) (datamodel.Node, error) {
-	var sub *string
-
-	if t.subject != did.Undef {
-		s := t.subject.String()
-		sub = &s
+	// 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")
 	}
 
-	// TODO
+	var aud *string
+
+	if t.audience != did.Undef {
+		a := t.audience.String()
+		aud = &a
+	}
 
 	var exp *int64
 	if t.expiration != nil {
@@ -208,14 +216,29 @@ func (t *Token) toIPLD(privKey crypto.PrivKey) (datamodel.Node, error) {
 		exp = &u
 	}
 
+	var iat *int64
+	if t.invokedAt != nil {
+		i := t.invokedAt.Unix()
+		iat = &i
+	}
+
 	model := &tokenPayloadModel{
 		Iss:   t.issuer.String(),
-		Aud:   t.audience.String(),
-		Sub:   sub,
+		Aud:   aud,
+		Sub:   t.subject.String(),
 		Cmd:   t.command.String(),
+		Args:  t.arguments,
+		Prf:   t.proof,
+		Meta:  t.meta,
 		Nonce: t.nonce,
-		Meta:  *t.meta,
 		Exp:   exp,
+		Iat:   iat,
+		Cause: t.cause,
+	}
+
+	// seems like it's a requirement to have a null meta if there are no values?
+	if len(model.Meta.Keys) == 0 {
+		model.Meta = nil
 	}
 
 	return envelope.ToIPLD(privKey, model)

token/invocation/ipld_test.go

@@ -0,0 +1,38 @@
+package invocation_test
+
+import (
+	"testing"
+	"time"
+
+	"github.com/stretchr/testify/assert"
+	"github.com/stretchr/testify/require"
+
+	"github.com/ucan-wg/go-ucan/token/invocation"
+)
+
+func TestSealUnsealRoundtrip(t *testing.T) {
+	t.Parallel()
+
+	privKey, iss, sub, cmd, args, prf, meta, err := setupExampleNew()
+	require.NoError(t, err)
+
+	tkn1, err := invocation.New(iss, sub, cmd, 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(),
+	)
+	require.NoError(t, err)
+
+	data, cid1, err := tkn1.ToSealed(privKey)
+	require.NoError(t, err)
+
+	tkn2, cid2, err := invocation.FromSealed(data)
+	require.NoError(t, err)
+
+	assert.Equal(t, cid1, cid2)
+	assert.Equal(t, tkn1, tkn2)
+}

token/invocation/options.go

@@ -0,0 +1,141 @@
+package invocation
+
+import (
+	"time"
+
+	"github.com/ipfs/go-cid"
+
+	"github.com/ucan-wg/go-ucan/did"
+)
+
+// Option is a type that allows optional fields to be set during the
+// creation of an invocation Token.
+type Option func(*Token) error
+
+// WithArgument adds a key/value pair to the Token's Arguments field.
+func WithArgument(key string, val any) Option {
+	return func(t *Token) error {
+		return t.arguments.Add(key, val)
+	}
+}
+
+// WithAudience sets the Token's audience to the provided did.DID.
+//
+// If the provided did.DID is the same as the Token's subject, the
+// audience is not set.
+func WithAudience(aud did.DID) Option {
+	return func(t *Token) error {
+		if t.subject.String() != aud.String() {
+			t.audience = aud
+		}
+
+		return nil
+	}
+}
+
+// WithMeta adds a key/value pair in the "meta" field.
+//
+// WithMeta can be used multiple times in the same call.
+// Accepted types for the value are: bool, string, int, int32, int64, []byte,
+// and ipld.Node.
+func WithMeta(key string, val any) Option {
+	return func(t *Token) error {
+		return t.meta.Add(key, val)
+	}
+}
+
+// WithEncryptedMetaString adds a key/value pair in the "meta" field.
+// The string value is encrypted with the given aesKey.
+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 aesKey.
+func WithEncryptedMetaBytes(key string, val, encryptionKey []byte) Option {
+	return func(t *Token) error {
+		return t.meta.AddEncrypted(key, val, encryptionKey)
+	}
+}
+
+// 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.  If you truly want to create an invocation Token
+// without a nonce, use the WithEmptyNonce Option which will set the
+// nonce to an empty byte array.
+func WithNonce(nonce []byte) Option {
+	return func(t *Token) error {
+		t.nonce = nonce
+
+		return nil
+	}
+}
+
+// WithEmptyNonce sets the Token's nonce to an empty byte slice as
+// suggested by the UCAN spec for invocation tokens that represent
+// idempotent operations.
+func WithEmptyNonce() Option {
+	return func(t *Token) error {
+		t.nonce = []byte{}
+
+		return nil
+	}
+}
+
+// WithExpiration set's the Token's optional "expiration" field to the
+// value of the provided time.Time.
+func WithExpiration(exp time.Time) Option {
+	return func(t *Token) error {
+		exp = exp.Round(time.Second)
+		t.expiration = &exp
+
+		return nil
+	}
+}
+
+// WithExpirationIn set's the Token's optional "expiration" field to
+// Now() plus the given duration.
+func WithExpirationIn(after time.Duration) Option {
+	return WithExpiration(time.Now().Add(after))
+}
+
+// WithInvokedAt sets the Token's invokedAt field to the provided
+// time.Time.
+//
+// If this Option is not provided, the invocation Token's iat field will
+// be set to the value of time.Now().  If you want to create an invocation
+// Token without this field being set, use the WithoutInvokedAt Option.
+func WithInvokedAt(iat time.Time) Option {
+	return func(t *Token) error {
+		t.invokedAt = &iat
+
+		return nil
+	}
+}
+
+// WithInvokedAtIn sets the Token's invokedAt field to Now() plus the
+// given duration.
+func WithInvokedAtIn(after time.Duration) Option {
+	return WithInvokedAt(time.Now().Add(after))
+}
+
+// WithoutInvokedAt clears the Token's invokedAt field.
+func WithoutInvokedAt() Option {
+	return func(t *Token) error {
+		t.invokedAt = nil
+
+		return nil
+	}
+}
+
+// WithCause sets the Token's cause field to the provided cid.Cid.
+func WithCause(cause *cid.Cid) Option {
+	return func(t *Token) error {
+		t.cause = cause
+
+		return nil
+	}
+}

token/invocation/proof.go

@@ -0,0 +1,141 @@
+package invocation
+
+import (
+	"fmt"
+	"time"
+
+	"github.com/ucan-wg/go-ucan/pkg/args"
+	"github.com/ucan-wg/go-ucan/pkg/policy"
+	"github.com/ucan-wg/go-ucan/token/delegation"
+)
+
+// # Invocation token validation
+//
+// Per the specification, invocation Tokens must be validated before the command is executed.
+// This validation effectively happens in multiple places in the codebase.
+// Steps 1 and 2 are the same for all token types.
+//
+//  1. When a token is read/unsealed from its containing envelope (`envelope` package):
+//     a. The envelope can be decoded.
+//     b. The envelope contains a Signature, VarsigHeader and Payload.
+//     c. The Payload contains an iss field that contains a valid `did:key`.
+//     d. The public key can be extracted from the `did:key`.
+//     e. The public key type is supported by go-ucan.
+//     f. The Signature can be decoded per the VarsigHeader.
+//     g. The SigPayload can be verified using the Signature and public key.
+//     h. The field key of the TokenPayload matches the expected tag.
+//
+//  2. When the token is created or passes step one (token constructor or decoder):
+//     a. All required fields are present
+//     b. All populated fields respect their own rules (example: a policy is legal)
+//
+//  3. When an unsealed invocation passes steps one and two for execution (verifyTimeBound below):
+//     a. The invocation cannot be expired (expiration in the future or absent).
+//     b. All the delegation must not be expired (expiration in the future or absent).
+//     c. All the delegation must be active (nbf in the past or absent).
+//
+//  4. When the proof chain is being validated (verifyProofs below):
+//     a. There must be at least one delegation in the proof chain.
+//     b. All referenced delegations must be available.
+//     c. The first proof must be issued to the Invoker (audience DID).
+//     d. The Issuer of each delegation must be the Audience in the next one.
+//     e. The last token must be a root delegation.
+//     f. The Subject of each delegation must equal the invocation's Audience field.
+//     g. The command of each delegation must "allow" the one before it.
+//
+//  5. If steps 1-4 pass:
+//     a. The policy must "match" the arguments. (verifyArgs below)
+//     b. The nonce (if present) is not reused. (out of scope for go-ucan)
+
+// verifyProofs controls that the proof chain allows the invocation:
+// - principal alignment
+// - command alignment
+func (t *Token) verifyProofs(delegations []*delegation.Token) error {
+	// There must be at least one delegation referenced - 4a
+	if len(delegations) < 1 {
+		return ErrNoProof
+	}
+
+	cmd := t.command
+	iss := t.issuer
+	aud := t.audience
+	if !aud.Defined() {
+		aud = t.subject
+	}
+
+	// control from the invocation to the root
+	for i, dlgCid := range t.proof {
+		dlg := delegations[i]
+
+		// The Subject of each delegation must equal the invocation's Audience field. - 4f
+		if dlg.Subject() != aud {
+			return fmt.Errorf("%w: delegation %s, expected %s, got %s", ErrWrongSub, dlgCid, aud, dlg.Subject())
+		}
+
+		// The first proof must be issued to the Invoker (audience DID). - 4c
+		// The Issuer of each delegation must be the Audience in the next one. - 4d
+		if dlg.Audience() != iss {
+			return fmt.Errorf("%w: delegation %s, expected %s, got %s", ErrBrokenChain, dlgCid, iss, dlg.Audience())
+		}
+		iss = dlg.Issuer()
+
+		// The command of each delegation must "allow" the one before it. - 4g
+		if !dlg.Command().Covers(cmd) {
+			return fmt.Errorf("%w: delegation %s, %s doesn't cover %s", ErrCommandNotCovered, dlgCid, dlg.Command(), cmd)
+		}
+		cmd = dlg.Command()
+	}
+
+	// The last prf value must be a root delegation (have the issuer field match the Subject field) - 4e
+	if last := delegations[len(delegations)-1]; last.Issuer() != last.Subject() {
+		return fmt.Errorf("%w: expected %s, got %s", ErrLastNotRoot, last.Subject(), last.Issuer())
+	}
+
+	return nil
+}
+
+func (t *Token) verifyTimeBound(dlgs []*delegation.Token) error {
+	return t.verifyTimeBoundAt(time.Now(), dlgs)
+}
+
+func (t *Token) verifyTimeBoundAt(at time.Time, delegations []*delegation.Token) error {
+	// The invocation cannot be expired (expiration in the future or absent). - 3a
+	if !t.IsValidAt(at) {
+		return fmt.Errorf("%w: invocation", ErrTokenInvalidNow)
+	}
+
+	for i, dlgCid := range t.proof {
+		dlg := delegations[i]
+
+		// All the delegation must not be expired (expiration in the future or absent). - 3b
+		// All the delegation must be active (nbf in the past or absent). - 3c
+		if !dlg.IsValidAt(at) {
+			return fmt.Errorf("%w: delegation %s", ErrTokenInvalidNow, dlgCid)
+		}
+	}
+	return nil
+}
+
+func (t *Token) verifyArgs(delegations []*delegation.Token, arguments *args.Args) error {
+	var count int
+	for i := range t.proof {
+		count += len(delegations[i].Policy())
+	}
+
+	policies := make(policy.Policy, 0, count)
+	for i := range t.proof {
+		policies = append(policies, delegations[i].Policy()...)
+	}
+
+	argsIpld, err := arguments.ToIPLD()
+	if err != nil {
+		return err
+	}
+
+	ok, statement := policies.Match(argsIpld)
+	if !ok {
+		return fmt.Errorf("the following UCAN policy is not satisfied: %v", statement.String())
+	}
+
+	return nil
+}

token/invocation/schema.go

@@ -5,10 +5,12 @@ import (
 	"fmt"
 	"sync"
 
+	"github.com/ipfs/go-cid"
 	"github.com/ipld/go-ipld-prime"
 	"github.com/ipld/go-ipld-prime/node/bindnode"
 	"github.com/ipld/go-ipld-prime/schema"
 
+	"github.com/ucan-wg/go-ucan/pkg/args"
 	"github.com/ucan-wg/go-ucan/pkg/meta"
 	"github.com/ucan-wg/go-ucan/token/internal/envelope"
 )
@@ -23,17 +25,17 @@ const Tag = "ucan/inv@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
 }
@@ -44,28 +46,34 @@ func payloadType() schema.Type {
 
 var _ envelope.Tokener = (*tokenPayloadModel)(nil)
 
-// TODO
 type tokenPayloadModel struct {
-	// Issuer DID (sender)
+	// The DID of the Invoker
 	Iss string
-	// Audience DID (receiver)
-	Aud string
-	// Principal that the chain is about (the Subject)
-	// optional: can be nil
-	Sub *string
+	// The DID of Subject being invoked
+	Sub string
+	// The DID of the intended Executor if different from the Subject
+	Aud *string
 
-	// The Command to eventually invoke
+	// The Command
 	Cmd string
+	// The Command's Arguments
+	Args *args.Args
+	// Delegations that prove the chain of authority
+	Prf []cid.Cid
+
+	// Arbitrary Metadata
+	Meta *meta.Meta
 
 	// A unique, random nonce
 	Nonce []byte
-
-	// Arbitrary Metadata
-	Meta meta.Meta
-
 	// The timestamp at which the Invocation becomes invalid
 	// optional: can be nil
 	Exp *int64
+	// The timestamp at which the Invocation was created
+	Iat *int64
+
+	// An optional CID of the Receipt that enqueued the Task
+	Cause *cid.Cid
 }
 
 func (e *tokenPayloadModel) Prototype() schema.TypedPrototype {

token/invocation/schema_test.go

@@ -0,0 +1,102 @@
+package invocation_test
+
+import (
+	"bytes"
+	"fmt"
+	"testing"
+
+	"github.com/libp2p/go-libp2p/core/crypto"
+	"github.com/stretchr/testify/assert"
+	"github.com/stretchr/testify/require"
+	"gotest.tools/v3/golden"
+
+	"github.com/ucan-wg/go-ucan/did/didtest"
+	"github.com/ucan-wg/go-ucan/token/internal/envelope"
+	"github.com/ucan-wg/go-ucan/token/invocation"
+)
+
+const (
+	issuerPrivKeyCfg = "CAESQK45xBfqIxRp7ZdRdck3tIJZKocCqvANQc925dCJhFwO7DJNA2j94zkF0TNx5mpXV0s6utfkFdHddWTaPVU6yZc="
+	newCID           = "zdpuAqY6Zypg4UnpbSUgDvYGneyFaTKaZevzxgSxV4rmv3Fpp"
+)
+
+func TestSchemaRoundTrip(t *testing.T) {
+	t.Parallel()
+
+	invocationJson := golden.Get(t, "new.dagjson")
+	privKey := privKey(t, issuerPrivKeyCfg)
+
+	t.Run("via buffers", func(t *testing.T) {
+		t.Parallel()
+
+		// format:    dagJson   -->   PayloadModel   -->   dagCbor   -->   PayloadModel   -->   dagJson
+		// function:      DecodeDagJson()           Seal()        Unseal()          EncodeDagJson()
+
+		p1, err := invocation.FromDagJson(invocationJson)
+		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))
+
+		p2, c2, err := invocation.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(invocationJson), string(readJson))
+	})
+
+	t.Run("via streaming", func(t *testing.T) {
+		t.Parallel()
+
+		buf := bytes.NewBuffer(invocationJson)
+
+		// format:    dagJson   -->   PayloadModel   -->   dagCbor   -->   PayloadModel   -->   dagJson
+		// function:      DecodeDagJson()           Seal()         Unseal()         EncodeDagJson()
+
+		p1, err := invocation.FromDagJsonReader(buf)
+		require.NoError(t, err)
+
+		cborBytes := &bytes.Buffer{}
+		id, err := p1.ToSealedWriter(cborBytes, privKey)
+		require.NoError(t, err)
+		assert.Equal(t, newCID, envelope.CIDToBase58BTC(id))
+
+		p2, c2, err := invocation.FromSealedReader(cborBytes)
+		require.NoError(t, err)
+		assert.Equal(t, envelope.CIDToBase58BTC(id), envelope.CIDToBase58BTC(c2))
+
+		readJson := &bytes.Buffer{}
+		require.NoError(t, p2.ToDagJsonWriter(readJson, privKey))
+
+		assert.JSONEq(t, string(invocationJson), readJson.String())
+	})
+
+	t.Run("fails with wrong PrivKey", func(t *testing.T) {
+		t.Parallel()
+
+		p1, err := invocation.FromDagJson(invocationJson)
+		require.NoError(t, err)
+
+		_, _, err = p1.ToSealed(didtest.PersonaBob.PrivKey())
+		require.EqualError(t, err, "private key doesn't match the issuer")
+	})
+}
+
+func privKey(t require.TestingT, privKeyCfg string) crypto.PrivKey {
+	privKeyMar, err := crypto.ConfigDecodeKey(privKeyCfg)
+	require.NoError(t, err)
+
+	privKey, err := crypto.UnmarshalPrivateKey(privKeyMar)
+	require.NoError(t, err)
+
+	return privKey
+}

token/invocation/testdata/new.dagjson

@@ -0,0 +1 @@
+[{"/":{"bytes":"o/vTvTs8SEkD9QL/eNhhW0fAng/SGBouywCbUnOfsF2RFHxaV02KTCyzgDxlJLZ2XN/Vk5igLmlKL3QIXMaeCQ"}},{"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":1730812145,"iss":"did:key:z6MkvMGkN5nbUQLBVqJhr13Zdqyh9rR1VuF16PuZbfocBxpv","meta":{"env":"development","tags":["blog","post","pr#123"]},"nonce":{"/":{"bytes":"q1AH6MJrqoTH6av7"}},"prf":[{"/":"bafyreigx3qxd2cndpe66j2mdssj773ecv7tqd7wovcnz5raguw6lj7sjoe"},{"/":"bafyreib34ira254zdqgehz6f2bhwme2ja2re3ltcalejv4x4tkcveujvpa"},{"/":"bafyreibkb66tpo2ixqx3fe5hmekkbuasrod6olt5bwm5u5pi726mduuwlq"}],"sub":"did:key:z6MkuFj35aiTL7YQiVMobuSeUQju92g7wZzufS3HAc6NFFcQ"}}]