Merge branch 'v1' into v1-policy-subset-selection

versatile segments matchers
refactor policy.Match as receiver
2024-09-24 19:41:39 +02:00 · 2024-09-24 19:36:01 +02:00 · 2024-09-24 11:36:31 +02:00 · 2024-09-24 11:33:06 +02:00
57 changed files with 546 additions and 2789 deletions
--- a/.github/workflows/bench.yml
+++ b/.github/workflows/bench.yml
@@ -1,34 +0,0 @@
-name: go continuous benchmark
-on:
-  push:
-    branches:
-      - v1
-
-permissions:
-  contents: write
-  deployments: write
-
-jobs:
-  benchmark:
-    name: Run Go continuous benchmark
-    runs-on: ubuntu-latest
-    steps:
-      - uses: actions/checkout@v4
-      - uses: actions/setup-go@v4
-        with:
-          go-version: "stable"
-      - name: Run benchmark
-        run: go test -v ./... -bench=. -run=xxx -benchmem | tee output.txt
-
-      - name: Store benchmark result
-        uses: benchmark-action/github-action-benchmark@v1
-        with:
-          name: Go Benchmark
-          tool: 'go'
-          output-file-path: output.txt
-          github-token: ${{ secrets.GITHUB_TOKEN }}
-          # Push and deploy GitHub pages branch automatically
-          auto-push: true
-          # Show alert with commit comment on detecting possible performance regression
-          alert-threshold: '200%'
-          comment-on-alert: true
--- a/did/did.go
+++ b/did/did.go
@@ -116,11 +116,3 @@ func Parse(str string) (DID, error) {
 	buf = append(buf, suffix...)
 	return DID{str: string(buf), code: DIDCore}, nil
 }
-
-func MustParse(str string) DID {
-	did, err := Parse(str)
-	if err != nil {
-		panic(err)
-	}
-	return did
-}
--- a/did/did_test.go
+++ b/did/did_test.go
@@ -2,8 +2,6 @@ package did

 import (
 	"testing"
-
-	"github.com/stretchr/testify/require"
 )

 func TestParseDIDKey(t *testing.T) {
@@ -17,18 +15,6 @@ func TestParseDIDKey(t *testing.T) {
 	}
 }

-func TestMustParseDIDKey(t *testing.T) {
-	str := "did:key:z6Mkod5Jr3yd5SC7UDueqK4dAAw5xYJYjksy722tA9Boxc4z"
-	require.NotPanics(t, func() {
-		d := MustParse(str)
-		require.Equal(t, str, d.String())
-	})
-	str = "did:key:z7Mkod5Jr3yd5SC7UDueqK4dAAw5xYJYjksy722tA9Boxc4z"
-	require.Panics(t, func() {
-		MustParse(str)
-	})
-}
-
 func TestDecodeDIDKey(t *testing.T) {
 	str := "did:key:z6Mkod5Jr3yd5SC7UDueqK4dAAw5xYJYjksy722tA9Boxc4z"
 	d0, err := Parse(str)
--- a/go.mod
+++ b/go.mod
@@ -1,6 +1,8 @@
 module github.com/ucan-wg/go-ucan

-go 1.23
+go 1.22
+
+toolchain go1.22.4

 require (
 	github.com/ipfs/go-cid v0.4.1
@@ -29,7 +31,6 @@ require (
 	golang.org/x/crypto v0.25.0 // indirect
 	golang.org/x/sys v0.22.0 // indirect
 	google.golang.org/protobuf v1.34.2 // indirect
-	gopkg.in/check.v1 v1.0.0-20190902080502-41f04d3bba15 // indirect
 	gopkg.in/yaml.v3 v3.0.1 // indirect
 	lukechampine.com/blake3 v1.3.0 // indirect
 )
--- a/go.sum
+++ b/go.sum
@@ -80,9 +80,8 @@ golang.org/x/text v0.3.0/go.mod h1:NqM8EUOU14njkJ3fqMW+pc6Ldnwhi/IjpwHt7yyuwOQ=
 golang.org/x/tools v0.0.0-20190328211700-ab21143f2384/go.mod h1:LCzVGOaR6xXOjkQ3onu1FJEFr0SW1gC7cKk1uF8kGRs=
 google.golang.org/protobuf v1.34.2 h1:6xV6lTsCfpGD21XK49h7MhtcApnLqkfYgPcdHftf6hg=
 google.golang.org/protobuf v1.34.2/go.mod h1:qYOHts0dSfpeUzUFpOMr/WGzszTmLH+DiWniOlNbLDw=
+gopkg.in/check.v1 v0.0.0-20161208181325-20d25e280405 h1:yhCVgyC4o1eVCa2tZl7eS0r+SDo693bJlVdllGtEeKM=
 gopkg.in/check.v1 v0.0.0-20161208181325-20d25e280405/go.mod h1:Co6ibVJAznAaIkqp8huTwlJQCZ016jof/cbN4VW5Yz0=
-gopkg.in/check.v1 v1.0.0-20190902080502-41f04d3bba15 h1:YR8cESwS4TdDjEe65xsg0ogRM/Nc3DYOhEAlW+xobZo=
-gopkg.in/check.v1 v1.0.0-20190902080502-41f04d3bba15/go.mod h1:Co6ibVJAznAaIkqp8huTwlJQCZ016jof/cbN4VW5Yz0=
 gopkg.in/yaml.v2 v2.2.2/go.mod h1:hI93XBmqTisBFMUTm0b8Fm+jr3Dg1NNxqwp+5A1VGuI=
 gopkg.in/yaml.v2 v2.4.0 h1:D8xgwECY7CYvx+Y2n4sBz93Jn9JRvxdiyyo8CTfuKaY=
 gopkg.in/yaml.v2 v2.4.0/go.mod h1:RDklbk79AGWmwhnvt/jBztapEOGDOx6ZbXqjP6csGnQ=
--- a/pkg/command/command.go
+++ b/pkg/command/command.go
@@ -16,12 +16,14 @@ var _ fmt.Stringer = (*Command)(nil)
 // by one or more slash-separated Segments of lowercase characters.
 //
 // [Command]: https://github.com/ucan-wg/spec#command
-type Command string
+type Command struct {
+	segments []string
+}

 // New creates a validated command from the provided list of segment strings.
 // An error is returned if an invalid Command would be formed
 func New(segments ...string) Command {
-	return Top().Join(segments...)
+	return Command{segments: segments}
 }

 // Parse verifies that the provided string contains the required
@@ -31,20 +33,20 @@ func New(segments ...string) Command {
 // [segment structure]: https://github.com/ucan-wg/spec#segment-structure
 func Parse(s string) (Command, error) {
 	if !strings.HasPrefix(s, "/") {
-		return "", ErrRequiresLeadingSlash
+		return Command{}, ErrRequiresLeadingSlash
 	}

 	if len(s) > 1 && strings.HasSuffix(s, "/") {
-		return "", ErrDisallowsTrailingSlash
+		return Command{}, ErrDisallowsTrailingSlash
 	}

 	if s != strings.ToLower(s) {
-		return "", ErrRequiresLowercase
+		return Command{}, ErrRequiresLowercase
 	}

 	// The leading slash will result in the first element from strings.Split
 	// being an empty string which is removed as strings.Join will ignore it.
-	return Command(s), nil
+	return Command{strings.Split(s, "/")[1:]}, nil
 }

 // MustParse is the same as Parse, but panic() if the parsing fail.
@@ -56,14 +58,14 @@ func MustParse(s string) Command {
 	return c
 }

-// Top is the most powerful capability.
+// [Top] is the most powerful capability.
 //
 // This function returns a Command that is a wildcard and therefore represents the
 // most powerful ability. As such, it should be handled with care and used sparingly.
 //
 // [Top]: https://github.com/ucan-wg/spec#-aka-top
 func Top() Command {
-	return Command(separator)
+	return New()
 }

 // IsValid returns true if the provided string is a valid UCAN command.
@@ -75,34 +77,17 @@ func IsValid(s string) bool {
 // Join appends segments to the end of this command using the required
 // segment separator.
 func (c Command) Join(segments ...string) Command {
-	size := 0
-	for _, s := range segments {
-		size += len(s)
-	}
-	if size == 0 {
-		return c
-	}
-	buf := make([]byte, 0, len(c)+size+len(segments))
-	buf = append(buf, []byte(c)...)
-	for _, s := range segments {
-		if s != "" {
-			if len(buf) > 1 {
-				buf = append(buf, separator...)
-			}
-			buf = append(buf, []byte(s)...)
-		}
-	}
-	return Command(buf)
+	return Command{append(c.segments, segments...)}
 }

 // 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)
+	return c.segments
 }

 // String returns the composed representation the command.  This is also
 // the required wire representation (before IPLD encoding occurs.)
 func (c Command) String() string {
-	return string(c)
+	return "/" + strings.Join(c.segments, "/")
 }
--- a/pkg/command/command_test.go
+++ b/pkg/command/command_test.go
@@ -13,66 +13,73 @@ func TestTop(t *testing.T) {
 }

 func TestIsValidCommand(t *testing.T) {
+	t.Parallel()
+
 	t.Run("succeeds when", func(t *testing.T) {
+		t.Parallel()
+
 		for _, testcase := range validTestcases(t) {
+			testcase := testcase
+
 			t.Run(testcase.name, func(t *testing.T) {
+				t.Parallel()
+
 				require.True(t, command.IsValid(testcase.inp))
 			})
 		}
 	})

 	t.Run("fails when", func(t *testing.T) {
+		t.Parallel()
+
 		for _, testcase := range invalidTestcases(t) {
+			testcase := testcase
+
 			t.Run(testcase.name, func(t *testing.T) {
+				t.Parallel()
+
 				require.False(t, command.IsValid(testcase.inp))
 			})
 		}
 	})
 }

-func TestNew(t *testing.T) {
-	require.Equal(t, command.Top(), command.New())
-	require.Equal(t, "/foo", command.New("foo").String())
-	require.Equal(t, "/foo/bar", command.New("foo", "bar").String())
-	require.Equal(t, "/foo/bar/baz", command.New("foo", "bar/baz").String())
-}
-
 func TestParseCommand(t *testing.T) {
+	t.Parallel()
+
 	t.Run("succeeds when", func(t *testing.T) {
+		t.Parallel()
+
 		for _, testcase := range validTestcases(t) {
+			testcase := testcase
+
 			t.Run(testcase.name, func(t *testing.T) {
+				t.Parallel()
+
 				cmd, err := command.Parse("/elem0/elem1/elem2")
 				require.NoError(t, err)
-				require.NotEmpty(t, cmd)
+				require.NotNil(t, cmd)
 			})
 		}
 	})

 	t.Run("fails when", func(t *testing.T) {
+		t.Parallel()
+
 		for _, testcase := range invalidTestcases(t) {
+			testcase := testcase
+
 			t.Run(testcase.name, func(t *testing.T) {
+				t.Parallel()
+
 				cmd, err := command.Parse(testcase.inp)
 				require.ErrorIs(t, err, testcase.err)
-				require.Zero(t, cmd)
+				require.Equal(t, command.Command{}, cmd)
 			})
 		}
 	})
 }

-func TestEquality(t *testing.T) {
-	require.True(t, command.MustParse("/foo/bar/baz") == command.MustParse("/foo/bar/baz"))
-	require.False(t, command.MustParse("/foo/bar/baz") == command.MustParse("/foo/bar/bazz"))
-	require.False(t, command.MustParse("/foo/bar") == command.MustParse("/foo/bar/baz"))
-}
-
-func TestJoin(t *testing.T) {
-	require.Equal(t, "/foo", command.Top().Join("foo").String())
-	require.Equal(t, "/foo/bar", command.Top().Join("foo/bar").String())
-	require.Equal(t, "/foo/bar", command.Top().Join("foo", "bar").String())
-	require.Equal(t, "/faz/boz/foo/bar", command.MustParse("/faz/boz").Join("foo/bar").String())
-	require.Equal(t, "/faz/boz/foo/bar", command.MustParse("/faz/boz").Join("foo", "bar").String())
-}
-
 type testcase struct {
 	name string
 	inp  string
--- a/pkg/container/Readme.md
+++ b/pkg/container/Readme.md
@@ -1,86 +0,0 @@
-# Token container
-
-## Why do I need that?
-
-Some common situation asks to package multiple tokens together:
- calling a service requires sending an invocation, alongside the matching delegations
- sending a series of revocations
- \<insert your application specific scenario here>
-
-The UCAN specification defines how a single token is serialized (envelope with signature, IPLD encoded as Dag-cbor), but it's entirely left open how to package multiple tokens together. To be clear, this is a correct thing to do for a specification, as different ways equally valid to solve that problem exists and can coexist. Any wire format holding a list of bytes would do (cbor, json, csv ...).
-
-**go-ucan** however, provide an opinionated implementation, which may or may not work in your situation. 
-
-Some experiment has been done over which format is appropriate, and two have been selected:
- **DAG-CBOR** of a list of bytes, as a low overhead option
- **CAR** file, as a somewhat common ways to cary arbitrary blocks of data
-
-Notably, **compression is not included**, even though it does work reasonably well. This is because your transport medium might already do it, or should.
-
-## Wire format consideration
-
-Several possible formats have been explored:
- CAR files (binary or base64)
- DAG-CBOR (binary or base64)
-
-Additionally, gzip and deflate compression has been experimented with.
-
-Below are the results in terms of storage used, as percentage and byte overhead over the raw tokens:
-
-| Token count | car | carBase64 | carGzip | carGzipBase64 | cbor | cborBase64 | cborGzip | cborGzipBase64 | cborFlate | cborFlateBase64 |
-|-------------|-----|-----------|---------|---------------|------|------------|----------|----------------|-----------|-----------------|
-| 1           | 15  | 54        | 7       | 42            | 0    | 35         | \-8      | 22             | \-12      | 16              |
-| 2           | 12  | 49        | \-12    | 15            | 0    | 34         | \-25     | 0              | \-28      | \-3             |
-| 3           | 11  | 48        | \-21    | 4             | 0    | 34         | \-32     | \-10           | \-34      | \-11            |
-| 4           | 10  | 47        | \-26    | \-1           | 0    | 34         | \-36     | \-15           | \-37      | \-17            |
-| 5           | 10  | 47        | \-28    | \-4           | 0    | 34         | \-38     | \-18           | \-40      | \-20            |
-| 6           | 10  | 47        | \-30    | \-7           | 0    | 34         | \-40     | \-20           | \-40      | \-20            |
-| 7           | 10  | 46        | \-31    | \-8           | 0    | 34         | \-41     | \-21           | \-42      | \-22            |
-| 8           | 9   | 46        | \-32    | \-10          | 0    | 34         | \-42     | \-22           | \-42      | \-23            |
-| 9           | 9   | 46        | \-33    | \-11          | 0    | 34         | \-43     | \-23           | \-43      | \-24            |
-| 10          | 9   | 46        | \-34    | \-12          | 0    | 34         | \-43     | \-25           | \-44      | \-25            |
-
-![Overhead %](img/overhead_percent.png)
-
-| Token count | car | carBase64 | carGzip | carGzipBase64 | cbor | cborBase64 | cborGzip | cborGzipBase64 | cborFlate | cborFlateBase64 |
-|-------------|-----|-----------|---------|---------------|------|------------|----------|----------------|-----------|-----------------|
-| 1           | 64  | 226       | 29      | 178           | 4    | 146        | \-35     | 94             | \-52      | 70              |
-| 2           | 102 | 412       | \-107   | 128           | 7    | 288        | \-211    | 0              | \-234     | \-32            |
-| 3           | 140 | 602       | \-270   | 58            | 10   | 430        | \-405    | \-126          | \-429     | \-146           |
-| 4           | 178 | 792       | \-432   | \-28          | 13   | 572        | \-602    | \-252          | \-617     | \-288           |
-| 5           | 216 | 978       | \-582   | \-94          | 16   | 714        | \-805    | \-386          | \-839     | \-418           |
-| 6           | 254 | 1168      | \-759   | \-176         | 19   | 856        | \-1001   | \-508          | \-1018    | \-520           |
-| 7           | 292 | 1358      | \-908   | \-246         | 22   | 998        | \-1204   | \-634          | \-1229    | \-650           |
-| 8           | 330 | 1544      | \-1085  | \-332         | 25   | 1140       | \-1398   | \-756          | \-1423    | \-792           |
-| 9           | 368 | 1734      | \-1257  | \-414         | 28   | 1282       | \-1614   | \-894          | \-1625    | \-930           |
-| 10          | 406 | 1924      | \-1408  | \-508         | 31   | 1424       | \-1804   | \-1040         | \-1826    | \-1060          |
-
-![img.png](img/overhead_bytes.png)
-
-Following is the performance aspect, with CPU usage and memory allocation:
-
-|                 | Write ns/op | Read ns/op | Write B/op | Read B/op | Write allocs/op | Read allocs/op |
-|-----------------|-------------|------------|------------|-----------|-----------------|----------------|
-| car             | 8451        | 1474630    | 17928      | 149437    | 59              | 2631           |
-| carBase64       | 16750       | 1437678    | 24232      | 151502    | 61              | 2633           |
-| carGzip         | 320253      | 1581412    | 823887     | 192272    | 76              | 2665           |
-| carGzipBase64   | 343305      | 1486269    | 828782     | 198543    | 77              | 2669           |
-| cbor            | 6419        | 1301554    | 16368      | 138891    | 25              | 2534           |
-| cborBase64      | 12860       | 1386728    | 20720      | 140962    | 26              | 2536           |
-| cborGzip        | 310106      | 1379146    | 822742     | 182003    | 42              | 2585           |
-| cborGzipBase64  | 317001      | 1462548    | 827640     | 189283    | 43              | 2594           |
-| cborFlate       | 327112      | 1555007    | 822473     | 181537    | 40              | 2591           |
-| cborFlateBase64 | 311276      | 1456562    | 826042     | 188665    | 41              | 2596           |
-
-(BEWARE: logarithmic scale)
-
-![img.png](img/cpu.png)
-![img_1.png](img/alloc_byte.png)
-![img_2.png](img/alloc_count.png)
-
-Conclusion:
- CAR files are heavy for this usage, notably because they carry the CIDs of the tokens
- compression works quite well and warrants its usage even with a single token
- DAG-CBOR outperform CAR files everywhere, and comes with a tiny ~3 bytes per token overhead.
-
-**Formats beside DAG-CBOR and CAR, with or without base64, have been removed. They are in the git history though.**
--- a/pkg/container/car.go
+++ b/pkg/container/car.go
@@ -1,263 +0,0 @@
-package container
-
-import (
-	"bufio"
-	"bytes"
-	"encoding/binary"
-	"fmt"
-	"io"
-	"iter"
-
-	"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/fluent/qp"
-	cidlink "github.com/ipld/go-ipld-prime/linking/cid"
-	"github.com/ipld/go-ipld-prime/node/basicnode"
-)
-
-/*
-	Note: below is essentially a re-implementation of the CAR file v1 read and write.
-	This exists here for two reasons:
-		- go-car's API forces to go through an IPLD getter or through a blockstore API
-		- generally, go-car is a very complex and large dependency
-*/
-
-// EmptyCid is a "zero" Cid: zero-length "identity" multihash with "raw" codec
-// It can be used to have at least one root in a CARv1 file (making it legal), yet
-// denote that it can be ignored.
-var EmptyCid = cid.MustParse([]byte{01, 55, 00, 00})
-
-type carBlock struct {
-	c    cid.Cid
-	data []byte
-}
-
-// writeCar writes a CARv1 file containing the blocks from the iterator.
-// If no roots are provided, a single EmptyCid is used as root to make the file
-// spec compliant.
-func writeCar(w io.Writer, roots []cid.Cid, blocks iter.Seq2[carBlock, error]) error {
-	if len(roots) == 0 {
-		roots = []cid.Cid{EmptyCid}
-	}
-	h := carHeader{
-		Roots:   roots,
-		Version: 1,
-	}
-	hb, err := h.Write()
-	if err != nil {
-		return err
-	}
-	err = ldWrite(w, hb)
-	if err != nil {
-		return err
-	}
-
-	for block, err := range blocks {
-		if err != nil {
-			return err
-		}
-		err = ldWrite(w, block.c.Bytes(), block.data)
-		if err != nil {
-			return err
-		}
-	}
-	return nil
-}
-
-// readCar reads a CARv1 file from the reader, and return a block iterator.
-// Roots are ignored.
-func readCar(r io.Reader) (roots []cid.Cid, blocks iter.Seq2[carBlock, error], err error) {
-	br := bufio.NewReader(r)
-
-	hb, err := ldRead(br)
-	if err != nil {
-		return nil, nil, err
-	}
-	h, err := readHeader(hb)
-	if err != nil {
-		return nil, nil, err
-	}
-	if h.Version != 1 {
-		return nil, nil, fmt.Errorf("invalid car version: %d", h.Version)
-	}
-
-	return h.Roots, func(yield func(block carBlock, err error) bool) {
-		for {
-			block, err := readBlock(br)
-			if err == io.EOF {
-				return
-			}
-			if err != nil {
-				if !yield(carBlock{}, err) {
-					return
-				}
-			}
-			if !yield(block, nil) {
-				return
-			}
-		}
-	}, nil
-}
-
-// readBlock reads a section from the reader and decode a (cid+data) block.
-func readBlock(r *bufio.Reader) (carBlock, error) {
-	raw, err := ldRead(r)
-	if err != nil {
-		return carBlock{}, err
-	}
-
-	n, c, err := cid.CidFromReader(bytes.NewReader(raw))
-	if err != nil {
-		return carBlock{}, err
-	}
-	data := raw[n:]
-
-	// integrity check
-	hashed, err := c.Prefix().Sum(data)
-	if err != nil {
-		return carBlock{}, err
-	}
-
-	if !hashed.Equals(c) {
-		return carBlock{}, fmt.Errorf("mismatch in content integrity, name: %s, data: %s", c, hashed)
-	}
-
-	return carBlock{c: c, data: data}, nil
-}
-
-// maxAllowedSectionSize dictates the maximum number of bytes that a CARv1 header
-// or section is allowed to occupy without causing a decode to error.
-// This cannot be supplied as an option, only adjusted as a global. You should
-// use v2#NewReader instead since it allows for options to be passed in.
-var maxAllowedSectionSize uint = 32 << 20 // 32MiB
-
-// ldRead performs a length-delimited read of a section from the reader.
-// A section is composed of an uint length followed by the data.
-func ldRead(r *bufio.Reader) ([]byte, error) {
-	if _, err := r.Peek(1); err != nil { // no more blocks, likely clean io.EOF
-		return nil, err
-	}
-
-	l, err := binary.ReadUvarint(r)
-	if err != nil {
-		if err == io.EOF {
-			return nil, io.ErrUnexpectedEOF // don't silently pretend this is a clean EOF
-		}
-		return nil, err
-	}
-	if l == 0 {
-		return nil, fmt.Errorf("invalid zero size section")
-	}
-
-	if l > uint64(maxAllowedSectionSize) { // Don't OOM
-		return nil, fmt.Errorf("malformed car; header is bigger than MaxAllowedSectionSize")
-	}
-
-	buf := make([]byte, l)
-	if _, err := io.ReadFull(r, buf); err != nil {
-		if err == io.EOF {
-			// we should be able to read the promised bytes, this is not normal
-			return nil, io.ErrUnexpectedEOF
-		}
-		return nil, err
-	}
-
-	return buf, nil
-}
-
-// ldWrite performs a length-delimited write of a section on the writer.
-// A section is composed of an uint length followed by the data.
-func ldWrite(w io.Writer, d ...[]byte) error {
-	var sum uint64
-	for _, s := range d {
-		sum += uint64(len(s))
-	}
-
-	buf := make([]byte, 8)
-	n := binary.PutUvarint(buf, sum)
-	_, err := w.Write(buf[:n])
-	if err != nil {
-		return err
-	}
-
-	for _, s := range d {
-		_, err = w.Write(s)
-		if err != nil {
-			return err
-		}
-	}
-
-	return nil
-}
-
-type carHeader struct {
-	Roots   []cid.Cid
-	Version uint64
-}
-
-const rootsKey = "roots"
-const versionKey = "version"
-
-func readHeader(data []byte) (*carHeader, error) {
-	var header carHeader
-
-	nd, err := ipld.Decode(data, dagcbor.Decode)
-	if err != nil {
-		return nil, err
-	}
-	if nd.Length() != 2 {
-		return nil, fmt.Errorf("malformed car header")
-	}
-	rootsNd, err := nd.LookupByString(rootsKey)
-	if err != nil {
-		return nil, fmt.Errorf("malformed car header")
-	}
-	it := rootsNd.ListIterator()
-	if it == nil {
-		return nil, fmt.Errorf("malformed car header")
-	}
-	header.Roots = make([]cid.Cid, 0, rootsNd.Length())
-	for !it.Done() {
-		_, nd, err := it.Next()
-		if err != nil {
-			return nil, err
-		}
-		lk, err := nd.AsLink()
-		if err != nil {
-			return nil, err
-		}
-		switch lk := lk.(type) {
-		case cidlink.Link:
-			header.Roots = append(header.Roots, lk.Cid)
-		default:
-			return nil, fmt.Errorf("malformed car header")
-		}
-	}
-	versionNd, err := nd.LookupByString(versionKey)
-	if err != nil {
-		return nil, fmt.Errorf("malformed car header")
-	}
-	version, err := versionNd.AsInt()
-	if err != nil {
-		return nil, fmt.Errorf("malformed car header")
-	}
-	header.Version = uint64(version)
-	return &header, nil
-}
-
-func (ch *carHeader) Write() ([]byte, error) {
-	nd, err := qp.BuildMap(basicnode.Prototype.Any, 2, func(ma datamodel.MapAssembler) {
-		qp.MapEntry(ma, rootsKey, qp.List(int64(len(ch.Roots)), func(la datamodel.ListAssembler) {
-			for _, root := range ch.Roots {
-				qp.ListEntry(la, qp.Link(cidlink.Link{Cid: root}))
-			}
-		}))
-		qp.MapEntry(ma, versionKey, qp.Int(1))
-	})
-	if err != nil {
-		return nil, err
-	}
-	return ipld.Encode(nd, dagcbor.Encode)
-}
--- a/pkg/container/car_test.go
+++ b/pkg/container/car_test.go
@@ -1,78 +0,0 @@
-package container
-
-import (
-	"bytes"
-	"os"
-	"testing"
-
-	"github.com/stretchr/testify/require"
-)
-
-func TestCarRoundTrip(t *testing.T) {
-	// this car file is a complex and legal CARv1 file
-	original, err := os.ReadFile("testdata/sample-v1.car")
-	require.NoError(t, err)
-
-	roots, it, err := readCar(bytes.NewReader(original))
-	require.NoError(t, err)
-
-	var blks []carBlock
-	for blk, err := range it {
-		require.NoError(t, err)
-		blks = append(blks, blk)
-	}
-
-	require.Len(t, blks, 1049)
-
-	buf := bytes.NewBuffer(nil)
-
-	err = writeCar(buf, roots, func(yield func(carBlock, error) bool) {
-		for _, blk := range blks {
-			if !yield(blk, nil) {
-				return
-			}
-		}
-	})
-	require.NoError(t, err)
-
-	// Bytes equal after the round-trip
-	require.Equal(t, original, buf.Bytes())
-}
-
-func FuzzCarRoundTrip(f *testing.F) {
-	example, err := os.ReadFile("testdata/sample-v1.car")
-	require.NoError(f, err)
-
-	f.Add(example)
-
-	f.Fuzz(func(t *testing.T, data []byte) {
-		roots, blocksIter, err := readCar(bytes.NewReader(data))
-		if err != nil {
-			// skip invalid binary
-			t.Skip()
-		}
-
-		// reading all the blocks, which force reading and verifying the full file
-		var blocks []carBlock
-		for block, err := range blocksIter {
-			if err != nil {
-				// error reading, invalid data
-				t.Skip()
-			}
-			blocks = append(blocks, block)
-		}
-
-		var buf bytes.Buffer
-		err = writeCar(&buf, roots, func(yield func(carBlock, error) bool) {
-			for _, blk := range blocks {
-				if !yield(blk, nil) {
-					return
-				}
-			}
-		})
-		require.NoError(t, err)
-
-		// test if the round-trip produce a byte-equal CAR
-		require.Equal(t, data, buf.Bytes())
-	})
-}
--- a/pkg/container/img/alloc_byte.png
+++ b/pkg/container/img/alloc_byte.png
--- a/pkg/container/img/alloc_count.png
+++ b/pkg/container/img/alloc_count.png
--- a/pkg/container/img/cpu.png
+++ b/pkg/container/img/cpu.png
--- a/pkg/container/img/overhead_bytes.png
+++ b/pkg/container/img/overhead_bytes.png
--- a/pkg/container/img/overhead_percent.png
+++ b/pkg/container/img/overhead_percent.png
--- a/pkg/container/reader.go
+++ b/pkg/container/reader.go
@@ -1,122 +0,0 @@
-package container
-
-import (
-	"encoding/base64"
-	"fmt"
-	"io"
-
-	"github.com/ipfs/go-cid"
-	"github.com/ipld/go-ipld-prime"
-	"github.com/ipld/go-ipld-prime/codec/dagcbor"
-	"github.com/ipld/go-ipld-prime/datamodel"
-
-	"github.com/ucan-wg/go-ucan/token"
-	"github.com/ucan-wg/go-ucan/token/delegation"
-	"github.com/ucan-wg/go-ucan/token/invocation"
-)
-
-var ErrNotFound = fmt.Errorf("not found")
-
-// Reader is a token container reader. It exposes the tokens conveniently decoded.
-type Reader map[cid.Cid]token.Token
-
-// GetToken returns an arbitrary decoded token, from its CID.
-// If not found, ErrNotFound is returned.
-func (ctn Reader) GetToken(cid cid.Cid) (token.Token, error) {
-	tkn, ok := ctn[cid]
-	if !ok {
-		return nil, ErrNotFound
-	}
-	return tkn, nil
-}
-
-// GetDelegation is the same as GetToken but only return a delegation.Token, with the right type.
-func (ctn Reader) GetDelegation(cid cid.Cid) (*delegation.Token, error) {
-	tkn, err := ctn.GetToken(cid)
-	if err != nil {
-		return nil, err
-	}
-	if tkn, ok := tkn.(*delegation.Token); ok {
-		return tkn, nil
-	}
-	return nil, fmt.Errorf("not a delegation token")
-}
-
-// GetInvocation returns the first found invocation.Token.
-// If none are found, ErrNotFound is returned.
-func (ctn Reader) GetInvocation() (*invocation.Token, error) {
-	for _, t := range ctn {
-		if inv, ok := t.(*invocation.Token); ok {
-			return inv, nil
-		}
-	}
-	return nil, ErrNotFound
-}
-
-func FromCar(r io.Reader) (Reader, error) {
-	_, it, err := readCar(r)
-	if err != nil {
-		return nil, err
-	}
-
-	ctn := make(Reader)
-
-	for block, err := range it {
-		if err != nil {
-			return nil, err
-		}
-
-		err = ctn.addToken(block.data)
-		if err != nil {
-			return nil, err
-		}
-	}
-
-	return ctn, nil
-}
-
-func FromCarBase64(r io.Reader) (Reader, error) {
-	return FromCar(base64.NewDecoder(base64.StdEncoding, r))
-}
-
-func FromCbor(r io.Reader) (Reader, error) {
-	n, err := ipld.DecodeStreaming(r, dagcbor.Decode)
-	if err != nil {
-		return nil, err
-	}
-	if n.Kind() != datamodel.Kind_List {
-		return nil, fmt.Errorf("not a list")
-	}
-
-	ctn := make(Reader, n.Length())
-
-	it := n.ListIterator()
-	for !it.Done() {
-		_, val, err := it.Next()
-		if err != nil {
-			return nil, err
-		}
-		data, err := val.AsBytes()
-		if err != nil {
-			return nil, err
-		}
-		err = ctn.addToken(data)
-		if err != nil {
-			return nil, err
-		}
-	}
-	return ctn, nil
-}
-
-func FromCborBase64(r io.Reader) (Reader, error) {
-	return FromCbor(base64.NewDecoder(base64.StdEncoding, r))
-}
-
-func (ctn Reader) addToken(data []byte) error {
-	tkn, c, err := token.FromSealed(data)
-	if err != nil {
-		return err
-	}
-	ctn[c] = tkn
-	return nil
-}
--- a/pkg/container/serial_test.go
+++ b/pkg/container/serial_test.go
@@ -1,184 +0,0 @@
-package container
-
-import (
-	"bytes"
-	"crypto/rand"
-	"fmt"
-	"io"
-	"strings"
-	"testing"
-	"time"
-
-	"github.com/ipfs/go-cid"
-	"github.com/libp2p/go-libp2p/core/crypto"
-	"github.com/stretchr/testify/require"
-
-	"github.com/ucan-wg/go-ucan/did"
-	"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"
-	"github.com/ucan-wg/go-ucan/token/delegation"
-)
-
-func TestContainerRoundTrip(t *testing.T) {
-	for _, tc := range []struct {
-		name   string
-		writer func(ctn Writer, w io.Writer) error
-		reader func(io.Reader) (Reader, error)
-	}{
-		{"car", Writer.ToCar, FromCar},
-		{"carBase64", Writer.ToCarBase64, FromCarBase64},
-		{"cbor", Writer.ToCbor, FromCbor},
-		{"cborBase64", Writer.ToCborBase64, FromCborBase64},
-	} {
-		t.Run(tc.name, func(t *testing.T) {
-			tokens := make(map[cid.Cid]*delegation.Token)
-			var dataSize int
-
-			writer := NewWriter()
-
-			for i := 0; i < 10; i++ {
-				dlg, c, data := randToken()
-				writer.AddSealed(c, data)
-				tokens[c] = dlg
-				dataSize += len(data)
-			}
-
-			buf := bytes.NewBuffer(nil)
-
-			err := tc.writer(writer, buf)
-			require.NoError(t, err)
-
-			t.Logf("data size %d", dataSize)
-			t.Logf("container overhead: %d%%, %d bytes", int(float32(buf.Len()-dataSize)/float32(dataSize)*100.0), buf.Len()-dataSize)
-
-			reader, err := tc.reader(bytes.NewReader(buf.Bytes()))
-			require.NoError(t, err)
-
-			for c, dlg := range tokens {
-				tknRead, err := reader.GetToken(c)
-				require.NoError(t, err)
-
-				// require.Equal fails as time.Time holds a wall time that is going to be
-				// different, even if it represents the same event.
-				// We need to do the following instead.
-
-				dlgRead := tknRead.(*delegation.Token)
-				require.Equal(t, dlg.Issuer(), dlgRead.Issuer())
-				require.Equal(t, dlg.Audience(), dlgRead.Audience())
-				require.Equal(t, dlg.Subject(), dlgRead.Subject())
-				require.Equal(t, dlg.Command(), dlgRead.Command())
-				require.Equal(t, dlg.Policy(), dlgRead.Policy())
-				require.Equal(t, dlg.Nonce(), dlgRead.Nonce())
-				require.True(t, dlg.Meta().Equals(dlgRead.Meta()))
-				if dlg.NotBefore() != nil {
-					// within 1s as the original value gets truncated to seconds when serialized
-					require.WithinDuration(t, *dlg.NotBefore(), *dlgRead.NotBefore(), time.Second)
-				}
-				if dlg.Expiration() != nil {
-					// within 1s as the original value gets truncated to seconds when serialized
-					require.WithinDuration(t, *dlg.Expiration(), *dlgRead.Expiration(), time.Second)
-				}
-			}
-		})
-	}
-}
-
-func BenchmarkContainerSerialisation(b *testing.B) {
-	var duration strings.Builder
-	var allocByte strings.Builder
-	var allocCount strings.Builder
-
-	for _, builder := range []strings.Builder{duration, allocByte, allocCount} {
-		builder.WriteString("car\tcarBase64\tcarGzip\tcarGzipBase64\tcbor\tcborBase64\tcborGzip\tcborGzipBase64\tcborFlate\tcborFlateBase64\n")
-	}
-
-	for _, tc := range []struct {
-		name   string
-		writer func(ctn Writer, w io.Writer) error
-		reader func(io.Reader) (Reader, error)
-	}{
-		{"car", Writer.ToCar, FromCar},
-		{"carBase64", Writer.ToCarBase64, FromCarBase64},
-		{"cbor", Writer.ToCbor, FromCbor},
-		{"cborBase64", Writer.ToCborBase64, FromCborBase64},
-	} {
-		writer := NewWriter()
-
-		for i := 0; i < 10; i++ {
-			_, c, data := randToken()
-			writer.AddSealed(c, data)
-		}
-
-		buf := bytes.NewBuffer(nil)
-		_ = tc.writer(writer, buf)
-
-		b.Run(tc.name+"_write", func(b *testing.B) {
-			b.ReportAllocs()
-			for i := 0; i < b.N; i++ {
-				buf := bytes.NewBuffer(nil)
-				_ = tc.writer(writer, buf)
-			}
-		})
-
-		b.Run(tc.name+"_read", func(b *testing.B) {
-			b.ReportAllocs()
-			for i := 0; i < b.N; i++ {
-				_, _ = tc.reader(bytes.NewReader(buf.Bytes()))
-			}
-		})
-	}
-}
-
-func randBytes(n int) []byte {
-	b := make([]byte, n)
-	_, _ = rand.Read(b)
-	return b
-}
-
-func randDID() (crypto.PrivKey, did.DID) {
-	privKey, _, err := crypto.GenerateEd25519Key(rand.Reader)
-	if err != nil {
-		panic(err)
-	}
-	d, err := did.FromPrivKey(privKey)
-	if err != nil {
-		panic(err)
-	}
-	return privKey, d
-}
-
-func randomString(length int) string {
-	b := make([]byte, length/2+1)
-	rand.Read(b)
-	return fmt.Sprintf("%x", b)[0:length]
-}
-
-func randToken() (*delegation.Token, cid.Cid, []byte) {
-	priv, iss := randDID()
-	_, aud := randDID()
-	cmd := command.New("foo", "bar")
-	pol := policy.MustConstruct(
-		policy.All(".[]",
-			policy.GreaterThan(".value", literal.Int(2)),
-		),
-	)
-
-	opts := []delegation.Option{
-		delegation.WithExpiration(time.Now().Add(time.Hour)),
-		delegation.WithSubject(iss),
-	}
-	for i := 0; i < 3; i++ {
-		opts = append(opts, delegation.WithMeta(randomString(8), randomString(10)))
-	}
-
-	t, err := delegation.New(priv, aud, cmd, pol, opts...)
-	if err != nil {
-		panic(err)
-	}
-	b, c, err := t.ToSealed(priv)
-	if err != nil {
-		panic(err)
-	}
-	return t, c, b
-}
--- a/pkg/container/testdata/sample-v1.car
+++ b/pkg/container/testdata/sample-v1.car
--- a/pkg/container/writer.go
+++ b/pkg/container/writer.go
@@ -1,61 +0,0 @@
-package container
-
-import (
-	"encoding/base64"
-	"io"
-
-	"github.com/ipfs/go-cid"
-	"github.com/ipld/go-ipld-prime"
-	"github.com/ipld/go-ipld-prime/codec/dagcbor"
-	"github.com/ipld/go-ipld-prime/datamodel"
-	"github.com/ipld/go-ipld-prime/fluent/qp"
-	"github.com/ipld/go-ipld-prime/node/basicnode"
-)
-
-// TODO: should we have a multibase to wrap the cbor? but there is no reader/write in go-multibase :-(
-
-// Writer is a token container writer. It provides a convenient way to aggregate and serialize tokens together.
-type Writer map[cid.Cid][]byte
-
-func NewWriter() Writer {
-	return make(Writer)
-}
-
-// AddSealed includes a "sealed" token (serialized with a ToSealed* function) in the container.
-func (ctn Writer) AddSealed(cid cid.Cid, data []byte) {
-	ctn[cid] = data
-}
-
-func (ctn Writer) ToCar(w io.Writer) error {
-	return writeCar(w, nil, func(yield func(carBlock, error) bool) {
-		for c, bytes := range ctn {
-			if !yield(carBlock{c: c, data: bytes}, nil) {
-				return
-			}
-		}
-	})
-}
-
-func (ctn Writer) ToCarBase64(w io.Writer) error {
-	w2 := base64.NewEncoder(base64.StdEncoding, w)
-	defer w2.Close()
-	return ctn.ToCar(w2)
-}
-
-func (ctn Writer) ToCbor(w io.Writer) error {
-	node, err := qp.BuildList(basicnode.Prototype.Any, int64(len(ctn)), func(la datamodel.ListAssembler) {
-		for _, bytes := range ctn {
-			qp.ListEntry(la, qp.Bytes(bytes))
-		}
-	})
-	if err != nil {
-		return err
-	}
-	return ipld.EncodeStreaming(w, node, dagcbor.Encode)
-}
-
-func (ctn Writer) ToCborBase64(w io.Writer) error {
-	w2 := base64.NewEncoder(base64.StdEncoding, w)
-	defer w2.Close()
-	return ctn.ToCbor(w2)
-}
--- a/pkg/meta/meta.go
+++ b/pkg/meta/meta.go
@@ -4,12 +4,10 @@ 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"
 )

 var ErrUnsupported = errors.New("failure adding unsupported type to meta")
@@ -125,41 +123,6 @@ func (m *Meta) Add(key string, val any) error {
 	return nil
 }

-// Equals tells if two Meta hold the same key/values.
-func (m *Meta) Equals(other *Meta) bool {
-	if len(m.Keys) != len(other.Keys) {
-		return false
-	}
-	if len(m.Values) != len(other.Values) {
-		return false
-	}
-	for _, key := range m.Keys {
-		if !ipld.DeepEqual(m.Values[key], other.Values[key]) {
-			return false
-		}
-	}
-	return true
-}
-
-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(key)
-		buf.WriteString(":")
-		buf.WriteString(printer.Sprint(node))
-	}
-
-	buf.WriteString("}")
-	return buf.String()
-}
-
 func fqtn(val any) string {
 	var name string

--- a/pkg/policy/ipld.go
+++ b/pkg/policy/ipld.go
@@ -61,7 +61,7 @@ func statementFromIPLD(path string, node datamodel.Node) (Statement, error) {
 			if err != nil {
 				return nil, err
 			}
-			return negation{statement: statement}, nil
+			return Not(statement), nil

 		case KindAnd, KindOr:
 			arg2, _ := node.LookupByIndex(1)
@@ -93,11 +93,11 @@ func statementFromIPLD(path string, node datamodel.Node) (Statement, error) {
 			if pattern.Kind() != datamodel.Kind_String {
 				return nil, ErrNotAString(combinePath(path, op, 2))
 			}
-			g, err := parseGlob(must.String(pattern))
+			res, err := Like(sel, must.String(pattern))
 			if err != nil {
 				return nil, ErrInvalidPattern(combinePath(path, op, 2), err)
 			}
-			return wildcard{selector: sel, pattern: g}, nil
+			return res, nil

 		case KindAll, KindAny:
 			sel, err := arg2AsSelector(op)
--- a/pkg/policy/literal/literal.go
+++ b/pkg/policy/literal/literal.go
@@ -1,13 +1,20 @@
-// Package literal holds a collection of functions to create IPLD types to use in policies, selector and args.
 package literal

 import (
-	"github.com/ipfs/go-cid"
 	"github.com/ipld/go-ipld-prime"
-	cidlink "github.com/ipld/go-ipld-prime/linking/cid"
 	"github.com/ipld/go-ipld-prime/node/basicnode"
 )

+func Node(n ipld.Node) ipld.Node {
+	return n
+}
+
+func Link(cid ipld.Link) ipld.Node {
+	nb := basicnode.Prototype.Link.NewBuilder()
+	nb.AssignLink(cid)
+	return nb.Build()
+}
+
 func Bool(val bool) ipld.Node {
 	nb := basicnode.Prototype.Bool.NewBuilder()
 	nb.AssignBool(val)
@@ -38,16 +45,6 @@ func Bytes(val []byte) ipld.Node {
 	return nb.Build()
 }

-func Link(link ipld.Link) ipld.Node {
-	nb := basicnode.Prototype.Link.NewBuilder()
-	nb.AssignLink(link)
-	return nb.Build()
-}
-
-func LinkCid(cid cid.Cid) ipld.Node {
-	return Link(cidlink.Link{Cid: cid})
-}
-
 func Null() ipld.Node {
 	nb := basicnode.Prototype.Any.NewBuilder()
 	nb.AssignNull()
--- a/pkg/policy/match.go
+++ b/pkg/policy/match.go
@@ -7,9 +7,28 @@ import (
 	"github.com/ipld/go-ipld-prime"
 	"github.com/ipld/go-ipld-prime/datamodel"
 	"github.com/ipld/go-ipld-prime/must"
+
+	"github.com/ucan-wg/go-ucan/pkg/policy/selector"
 )

-// Match determines if the IPLD node satisfies the policy.
+func (p Policy) Filter(sel selector.Selector) Policy {
+	return p.FilterWithMatcher(sel, selector.SegmentEquals)
+}
+
+// FilterWithMatcher extracts a subset of the policy related to the specified selector,
+// by matching each segment using the given selector.SegmentMatcher.
+func (p Policy) FilterWithMatcher(sel selector.Selector, matcher selector.SegmentMatcher) Policy {
+	var filtered Policy
+	for _, stmt := range p {
+		if stmt.Selector().Matches(sel, matcher) {
+			filtered = append(filtered, stmt)
+		}
+	}
+
+	return filtered
+}
+
+// Match determines if the IPLD node matches the policy document.
 func (p Policy) Match(node datamodel.Node) bool {
 	for _, stmt := range p {
 		ok := matchStatement(stmt, node)
@@ -17,40 +36,34 @@ func (p Policy) Match(node datamodel.Node) bool {
 			return false
 		}
 	}
+
 	return true
 }

-// Filter performs a recursive filtering of the Statement, and prunes what doesn't match the given path
-func (p Policy) Filter(path ...string) Policy {
-	var filtered Policy
-
-	for _, stmt := range p {
-		newChild, remain := filter(stmt, path)
-		if newChild != nil && len(remain) == 0 {
-			filtered = append(filtered, newChild)
-		}
-	}
-
-	return filtered
-}
-
 func matchStatement(statement Statement, node ipld.Node) bool {
 	switch statement.Kind() {
 	case KindEqual:
 		if s, ok := statement.(equality); ok {
-			one, _, err := s.selector.Select(node)
+			one, many, err := selector.Select(s.selector, node)
 			if err != nil {
 				return false
 			}
 			if one != nil {
 				return datamodel.DeepEqual(s.value, one)
 			}
+			if many != nil {
+				for _, n := range many {
+					if eq := datamodel.DeepEqual(s.value, n); eq {
+						return true
+					}
+				}
+			}

 			return false
 		}
 	case KindGreaterThan:
 		if s, ok := statement.(equality); ok {
-			one, _, err := s.selector.Select(node)
+			one, _, err := selector.Select(s.selector, node)
 			if err != nil || one == nil {
 				return false
 			}
@@ -58,7 +71,7 @@ func matchStatement(statement Statement, node ipld.Node) bool {
 		}
 	case KindGreaterThanOrEqual:
 		if s, ok := statement.(equality); ok {
-			one, _, err := s.selector.Select(node)
+			one, _, err := selector.Select(s.selector, node)
 			if err != nil || one == nil {
 				return false
 			}
@@ -66,7 +79,7 @@ func matchStatement(statement Statement, node ipld.Node) bool {
 		}
 	case KindLessThan:
 		if s, ok := statement.(equality); ok {
-			one, _, err := s.selector.Select(node)
+			one, _, err := selector.Select(s.selector, node)
 			if err != nil || one == nil {
 				return false
 			}
@@ -74,7 +87,7 @@ func matchStatement(statement Statement, node ipld.Node) bool {
 		}
 	case KindLessThanOrEqual:
 		if s, ok := statement.(equality); ok {
-			one, _, err := s.selector.Select(node)
+			one, _, err := selector.Select(s.selector, node)
 			if err != nil || one == nil {
 				return false
 			}
@@ -109,7 +122,7 @@ func matchStatement(statement Statement, node ipld.Node) bool {
 		}
 	case KindLike:
 		if s, ok := statement.(wildcard); ok {
-			one, _, err := s.selector.Select(node)
+			one, _, err := selector.Select(s.selector, node)
 			if err != nil || one == nil {
 				return false
 			}
@@ -121,72 +134,31 @@ func matchStatement(statement Statement, node ipld.Node) bool {
 		}
 	case KindAll:
 		if s, ok := statement.(quantifier); ok {
-			one, many, err := s.selector.Select(node)
-			if err != nil {
+			_, many, err := selector.Select(s.selector, node)
+			if err != nil || many == nil {
 				return false
 			}
-
-			if one != nil {
-				it := one.ListIterator()
-				if it != nil {
-					for !it.Done() {
-						_, v, err := it.Next()
-						if err != nil {
-							return false
-						}
-						ok := matchStatement(s.statement, v)
-						if !ok {
-							return false
-						}
-					}
-				} else {
-					ok := matchStatement(s.statement, one)
-					if !ok {
-						return false
-					}
+			for _, n := range many {
+				ok := matchStatement(s.statement, n)
+				if !ok {
+					return false
 				}
 			}
-
-			if len(many) > 0 {
-				for _, n := range many {
-					ok := matchStatement(s.statement, n)
-					if !ok {
-						return false
-					}
-				}
-			}
-
 			return true
 		}
 	case KindAny:
 		if s, ok := statement.(quantifier); ok {
-			one, many, err := s.selector.Select(node)
+			one, many, err := selector.Select(s.selector, node)
 			if err != nil {
 				return false
 			}
-
 			if one != nil {
-				it := one.ListIterator()
-				if it != nil {
-					for !it.Done() {
-						_, v, err := it.Next()
-						if err != nil {
-							return false
-						}
-						ok := matchStatement(s.statement, v)
-						if ok {
-							return true
-						}
-					}
-				} else {
-					ok := matchStatement(s.statement, one)
-					if ok {
-						return true
-					}
+				ok := matchStatement(s.statement, one)
+				if ok {
+					return true
 				}
 			}
-
-			if len(many) > 0 {
+			if many != nil {
 				for _, n := range many {
 					ok := matchStatement(s.statement, n)
 					if ok {
@@ -201,70 +173,6 @@ func matchStatement(statement Statement, node ipld.Node) bool {
 	panic(fmt.Errorf("unimplemented statement kind: %s", statement.Kind()))
 }

-// filter performs a recursive filtering of the Statement, and prunes what doesn't match the given path
-func filter(stmt Statement, path []string) (Statement, []string) {
-	// For each kind, we do some of the following if it applies:
-	// - test the path against the selector, consuming segments
-	// - for terminal statements (equality, wildcard), require all the segments to have been consumed
-	// - recursively filter child (negation, quantifier) or children (connective) statements with the remaining path
-	switch stmt.(type) {
-	case equality:
-		match, remain := stmt.(equality).selector.MatchPath(path...)
-		if match && len(remain) == 0 {
-			return stmt, remain
-		}
-		return nil, nil
-	case negation:
-		newChild, remain := filter(stmt.(negation).statement, path)
-		if newChild != nil && len(remain) == 0 {
-			return negation{
-				statement: newChild,
-			}, nil
-		}
-		return nil, nil
-	case connective:
-		var newChildren []Statement
-		for _, child := range stmt.(connective).statements {
-			newChild, remain := filter(child, path)
-			if newChild != nil && len(remain) == 0 {
-				newChildren = append(newChildren, newChild)
-			}
-		}
-		if len(newChildren) == 0 {
-			return nil, nil
-		}
-		return connective{
-			kind:       stmt.(connective).kind,
-			statements: newChildren,
-		}, nil
-	case wildcard:
-		match, remain := stmt.(wildcard).selector.MatchPath(path...)
-		if match && len(remain) == 0 {
-			return stmt, remain
-		}
-		return nil, nil
-	case quantifier:
-		match, remain := stmt.(quantifier).selector.MatchPath(path...)
-		if match && len(remain) == 0 {
-			return stmt, remain
-		}
-		if !match {
-			return nil, nil
-		}
-		newChild, remain := filter(stmt.(quantifier).statement, remain)
-		if newChild != nil && len(remain) == 0 {
-			return quantifier{
-				kind:      stmt.(quantifier).kind,
-				selector:  stmt.(quantifier).selector,
-				statement: newChild,
-			}, nil
-		}
-		return nil, nil
-	default:
-		panic(fmt.Errorf("unimplemented statement kind: %s", stmt.Kind()))
-	}
-}
-
 func isOrdered(expected ipld.Node, actual ipld.Node, satisfies func(order int) bool) bool {
 	if expected.Kind() == ipld.Kind_Int && actual.Kind() == ipld.Kind_Int {
 		a := must.Int(actual)
--- a/pkg/policy/match_test.go
+++ b/pkg/policy/match_test.go
@@ -1,8 +1,9 @@
 package policy

 import (
+	"encoding/json"
 	"fmt"
-	"strings"
+	"reflect"
 	"testing"

 	"github.com/ipfs/go-cid"
@@ -10,9 +11,11 @@ import (
 	"github.com/ipld/go-ipld-prime/codec/dagjson"
 	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"
+	"github.com/ucan-wg/go-ucan/pkg/policy/selector"
 )

 func TestMatch(t *testing.T) {
@@ -23,15 +26,15 @@ func TestMatch(t *testing.T) {
 			nb.AssignString("test")
 			nd := nb.Build()

-			pol := MustConstruct(Equal(".", literal.String("test")))
+			pol := Policy{Equal(selector.MustParse("."), literal.String("test"))}
 			ok := pol.Match(nd)
 			require.True(t, ok)

-			pol = MustConstruct(Equal(".", literal.String("test2")))
+			pol = Policy{Equal(selector.MustParse("."), literal.String("test2"))}
 			ok = pol.Match(nd)
 			require.False(t, ok)

-			pol = MustConstruct(Equal(".", literal.Int(138)))
+			pol = Policy{Equal(selector.MustParse("."), literal.Int(138))}
 			ok = pol.Match(nd)
 			require.False(t, ok)
 		})
@@ -42,15 +45,15 @@ func TestMatch(t *testing.T) {
 			nb.AssignInt(138)
 			nd := nb.Build()

-			pol := MustConstruct(Equal(".", literal.Int(138)))
+			pol := Policy{Equal(selector.MustParse("."), literal.Int(138))}
 			ok := pol.Match(nd)
 			require.True(t, ok)

-			pol = MustConstruct(Equal(".", literal.Int(1138)))
+			pol = Policy{Equal(selector.MustParse("."), literal.Int(1138))}
 			ok = pol.Match(nd)
 			require.False(t, ok)

-			pol = MustConstruct(Equal(".", literal.String("138")))
+			pol = Policy{Equal(selector.MustParse("."), literal.String("138"))}
 			ok = pol.Match(nd)
 			require.False(t, ok)
 		})
@@ -61,15 +64,15 @@ func TestMatch(t *testing.T) {
 			nb.AssignFloat(1.138)
 			nd := nb.Build()

-			pol := MustConstruct(Equal(".", literal.Float(1.138)))
+			pol := Policy{Equal(selector.MustParse("."), literal.Float(1.138))}
 			ok := pol.Match(nd)
 			require.True(t, ok)

-			pol = MustConstruct(Equal(".", literal.Float(11.38)))
+			pol = Policy{Equal(selector.MustParse("."), literal.Float(11.38))}
 			ok = pol.Match(nd)
 			require.False(t, ok)

-			pol = MustConstruct(Equal(".", literal.String("138")))
+			pol = Policy{Equal(selector.MustParse("."), literal.String("138"))}
 			ok = pol.Match(nd)
 			require.False(t, ok)
 		})
@@ -83,15 +86,15 @@ func TestMatch(t *testing.T) {
 			nb.AssignLink(l0)
 			nd := nb.Build()

-			pol := MustConstruct(Equal(".", literal.Link(l0)))
+			pol := Policy{Equal(selector.MustParse("."), literal.Link(l0))}
 			ok := pol.Match(nd)
 			require.True(t, ok)

-			pol = MustConstruct(Equal(".", literal.Link(l1)))
+			pol = Policy{Equal(selector.MustParse("."), literal.Link(l1))}
 			ok = pol.Match(nd)
 			require.False(t, ok)

-			pol = MustConstruct(Equal(".", literal.String("bafybeif4owy5gno5lwnixqm52rwqfodklf76hsetxdhffuxnplvijskzqq")))
+			pol = Policy{Equal(selector.MustParse("."), literal.String("bafybeif4owy5gno5lwnixqm52rwqfodklf76hsetxdhffuxnplvijskzqq"))}
 			ok = pol.Match(nd)
 			require.False(t, ok)
 		})
@@ -105,19 +108,19 @@ func TestMatch(t *testing.T) {
 			ma.Finish()
 			nd := nb.Build()

-			pol := MustConstruct(Equal(".foo", literal.String("bar")))
+			pol := Policy{Equal(selector.MustParse(".foo"), literal.String("bar"))}
 			ok := pol.Match(nd)
 			require.True(t, ok)

-			pol = MustConstruct(Equal(".[\"foo\"]", literal.String("bar")))
+			pol = Policy{Equal(selector.MustParse(".[\"foo\"]"), literal.String("bar"))}
 			ok = pol.Match(nd)
 			require.True(t, ok)

-			pol = MustConstruct(Equal(".foo", literal.String("baz")))
+			pol = Policy{Equal(selector.MustParse(".foo"), literal.String("baz"))}
 			ok = pol.Match(nd)
 			require.False(t, ok)

-			pol = MustConstruct(Equal(".foobar", literal.String("bar")))
+			pol = Policy{Equal(selector.MustParse(".foobar"), literal.String("bar"))}
 			ok = pol.Match(nd)
 			require.False(t, ok)
 		})
@@ -130,11 +133,11 @@ func TestMatch(t *testing.T) {
 			la.Finish()
 			nd := nb.Build()

-			pol := MustConstruct(Equal(".[0]", literal.String("foo")))
+			pol := Policy{Equal(selector.MustParse(".[0]"), literal.String("foo"))}
 			ok := pol.Match(nd)
 			require.True(t, ok)

-			pol = MustConstruct(Equal(".[1]", literal.String("foo")))
+			pol = Policy{Equal(selector.MustParse(".[1]"), literal.String("foo"))}
 			ok = pol.Match(nd)
 			require.False(t, ok)
 		})
@@ -147,7 +150,7 @@ func TestMatch(t *testing.T) {
 			nb.AssignInt(138)
 			nd := nb.Build()

-			pol := MustConstruct(GreaterThan(".", literal.Int(1)))
+			pol := Policy{GreaterThan(selector.MustParse("."), literal.Int(1))}
 			ok := pol.Match(nd)
 			require.True(t, ok)
 		})
@@ -158,11 +161,11 @@ func TestMatch(t *testing.T) {
 			nb.AssignInt(138)
 			nd := nb.Build()

-			pol := MustConstruct(GreaterThanOrEqual(".", literal.Int(1)))
+			pol := Policy{GreaterThanOrEqual(selector.MustParse("."), literal.Int(1))}
 			ok := pol.Match(nd)
 			require.True(t, ok)

-			pol = MustConstruct(GreaterThanOrEqual(".", literal.Int(138)))
+			pol = Policy{GreaterThanOrEqual(selector.MustParse("."), literal.Int(138))}
 			ok = pol.Match(nd)
 			require.True(t, ok)
 		})
@@ -173,7 +176,7 @@ func TestMatch(t *testing.T) {
 			nb.AssignFloat(1.38)
 			nd := nb.Build()

-			pol := MustConstruct(GreaterThan(".", literal.Float(1)))
+			pol := Policy{GreaterThan(selector.MustParse("."), literal.Float(1))}
 			ok := pol.Match(nd)
 			require.True(t, ok)
 		})
@@ -184,11 +187,11 @@ func TestMatch(t *testing.T) {
 			nb.AssignFloat(1.38)
 			nd := nb.Build()

-			pol := MustConstruct(GreaterThanOrEqual(".", literal.Float(1)))
+			pol := Policy{GreaterThanOrEqual(selector.MustParse("."), literal.Float(1))}
 			ok := pol.Match(nd)
 			require.True(t, ok)

-			pol = MustConstruct(GreaterThanOrEqual(".", literal.Float(1.38)))
+			pol = Policy{GreaterThanOrEqual(selector.MustParse("."), literal.Float(1.38))}
 			ok = pol.Match(nd)
 			require.True(t, ok)
 		})
@@ -199,7 +202,7 @@ func TestMatch(t *testing.T) {
 			nb.AssignInt(138)
 			nd := nb.Build()

-			pol := MustConstruct(LessThan(".", literal.Int(1138)))
+			pol := Policy{LessThan(selector.MustParse("."), literal.Int(1138))}
 			ok := pol.Match(nd)
 			require.True(t, ok)
 		})
@@ -210,11 +213,11 @@ func TestMatch(t *testing.T) {
 			nb.AssignInt(138)
 			nd := nb.Build()

-			pol := MustConstruct(LessThanOrEqual(".", literal.Int(1138)))
+			pol := Policy{LessThanOrEqual(selector.MustParse("."), literal.Int(1138))}
 			ok := pol.Match(nd)
 			require.True(t, ok)

-			pol = MustConstruct(LessThanOrEqual(".", literal.Int(138)))
+			pol = Policy{LessThanOrEqual(selector.MustParse("."), literal.Int(138))}
 			ok = pol.Match(nd)
 			require.True(t, ok)
 		})
@@ -226,11 +229,11 @@ func TestMatch(t *testing.T) {
 		nb.AssignBool(false)
 		nd := nb.Build()

-		pol := MustConstruct(Not(Equal(".", literal.Bool(true))))
+		pol := Policy{Not(Equal(selector.MustParse("."), literal.Bool(true)))}
 		ok := pol.Match(nd)
 		require.True(t, ok)

-		pol = MustConstruct(Not(Equal(".", literal.Bool(false))))
+		pol = Policy{Not(Equal(selector.MustParse("."), literal.Bool(false)))}
 		ok = pol.Match(nd)
 		require.False(t, ok)
 	})
@@ -241,25 +244,25 @@ func TestMatch(t *testing.T) {
 		nb.AssignInt(138)
 		nd := nb.Build()

-		pol := MustConstruct(
+		pol := Policy{
 			And(
-				GreaterThan(".", literal.Int(1)),
-				LessThan(".", literal.Int(1138)),
+				GreaterThan(selector.MustParse("."), literal.Int(1)),
+				LessThan(selector.MustParse("."), literal.Int(1138)),
 			),
-		)
+		}
 		ok := pol.Match(nd)
 		require.True(t, ok)

-		pol = MustConstruct(
+		pol = Policy{
 			And(
-				GreaterThan(".", literal.Int(1)),
-				Equal(".", literal.Int(1138)),
+				GreaterThan(selector.MustParse("."), literal.Int(1)),
+				Equal(selector.MustParse("."), literal.Int(1138)),
 			),
-		)
+		}
 		ok = pol.Match(nd)
 		require.False(t, ok)

-		pol = MustConstruct(And())
+		pol = Policy{And()}
 		ok = pol.Match(nd)
 		require.True(t, ok)
 	})
@@ -270,25 +273,25 @@ func TestMatch(t *testing.T) {
 		nb.AssignInt(138)
 		nd := nb.Build()

-		pol := MustConstruct(
+		pol := Policy{
 			Or(
-				GreaterThan(".", literal.Int(138)),
-				LessThan(".", literal.Int(1138)),
+				GreaterThan(selector.MustParse("."), literal.Int(138)),
+				LessThan(selector.MustParse("."), literal.Int(1138)),
 			),
-		)
+		}
 		ok := pol.Match(nd)
 		require.True(t, ok)

-		pol = MustConstruct(
+		pol = Policy{
 			Or(
-				GreaterThan(".", literal.Int(138)),
-				Equal(".", literal.Int(1138)),
+				GreaterThan(selector.MustParse("."), literal.Int(138)),
+				Equal(selector.MustParse("."), literal.Int(1138)),
 			),
-		)
+		}
 		ok = pol.Match(nd)
 		require.False(t, ok)

-		pol = MustConstruct(Or())
+		pol = Policy{Or()}
 		ok = pol.Match(nd)
 		require.True(t, ok)
 	})
@@ -309,7 +312,10 @@ func TestMatch(t *testing.T) {
 					nb.AssignString(s)
 					nd := nb.Build()

-					pol := MustConstruct(Like(".", pattern))
+					statement, err := Like(selector.MustParse("."), pattern)
+					require.NoError(t, err)
+
+					pol := Policy{statement}
 					ok := pol.Match(nd)
 					require.True(t, ok)
 				})
@@ -330,7 +336,10 @@ func TestMatch(t *testing.T) {
 					nb.AssignString(s)
 					nd := nb.Build()

-					pol := MustConstruct(Like(".", pattern))
+					statement, err := Like(selector.MustParse("."), pattern)
+					require.NoError(t, err)
+
+					pol := Policy{statement}
 					ok := pol.Match(nd)
 					require.False(t, ok)
 				})
@@ -361,11 +370,21 @@ func TestMatch(t *testing.T) {
 			la.Finish()
 			nd := nb.Build()

-			pol := MustConstruct(All(".[]", GreaterThan(".value", literal.Int(2))))
+			pol := Policy{
+				All(
+					selector.MustParse(".[]"),
+					GreaterThan(selector.MustParse(".value"), literal.Int(2)),
+				),
+			}
 			ok := pol.Match(nd)
 			require.True(t, ok)

-			pol = MustConstruct(All(".[]", GreaterThan(".value", literal.Int(20))))
+			pol = Policy{
+				All(
+					selector.MustParse(".[]"),
+					GreaterThan(selector.MustParse(".value"), literal.Int(20)),
+				),
+			}
 			ok = pol.Match(nd)
 			require.False(t, ok)
 		})
@@ -382,11 +401,21 @@ func TestMatch(t *testing.T) {
 			la.Finish()
 			nd := nb.Build()

-			pol := MustConstruct(Any(".[]", GreaterThan(".value", literal.Int(60))))
+			pol := Policy{
+				Any(
+					selector.MustParse(".[]"),
+					GreaterThan(selector.MustParse(".value"), literal.Int(60)),
+				),
+			}
 			ok := pol.Match(nd)
 			require.True(t, ok)

-			pol = MustConstruct(Any(".[]", GreaterThan(".value", literal.Int(100))))
+			pol = Policy{
+				Any(
+					selector.MustParse(".[]"),
+					GreaterThan(selector.MustParse(".value"), literal.Int(100)),
+				),
+			}
 			ok = pol.Match(nd)
 			require.False(t, ok)
 		})
@@ -515,101 +544,99 @@ func FuzzMatch(f *testing.F) {
 }

 func TestPolicyFilter(t *testing.T) {
-	pol := MustConstruct(
-		Any(".http", And(
-			Equal(".method", literal.String("GET")),
-			Equal(".path", literal.String("/foo")),
-		)),
-		Equal(".http", literal.String("foobar")),
-		All(".jsonrpc.foo", Or(
-			Not(Equal(".bar", literal.String("foo"))),
-			Equal(".", literal.String("foo")),
-			Like(".boo", "abcd"),
-			Like(".boo", "*bcd"),
-		)),
-	)
+	sel1 := selector.Selector{selector.NewFieldSegment("http")}
+	sel2 := selector.Selector{selector.NewFieldSegment("jsonrpc")}

-	for _, tc := range []struct {
-		path     string
-		expected Policy
-	}{
-		{
-			path: "http",
-			expected: MustConstruct(
-				Any(".http", And(
-					Equal(".method", literal.String("GET")),
-					Equal(".path", literal.String("/foo")),
-				)),
-				Equal(".http", literal.String("foobar")),
-			),
-		},
-		{
-			path: "http,method",
-			expected: MustConstruct(
-				Any(".http", And(
-					Equal(".method", literal.String("GET")),
-				)),
-			),
-		},
-		{
-			path: "http,path",
-			expected: MustConstruct(
-				Any(".http", And(
-					Equal(".path", literal.String("/foo")),
-				)),
-			),
-		},
-		{
-			path:     "http,foo",
-			expected: Policy{},
-		},
-		{
-			path: "jsonrpc",
-			expected: MustConstruct(
-				All(".jsonrpc.foo", Or(
-					Not(Equal(".bar", literal.String("foo"))),
-					Equal(".", literal.String("foo")),
-					Like(".boo", "abcd"),
-					Like(".boo", "*bcd"),
-				)),
-			),
-		},
-		{
-			path:     "jsonrpc,baz",
-			expected: Policy{},
-		},
-		{
-			path: "jsonrpc,foo",
-			expected: MustConstruct(
-				All(".jsonrpc.foo", Or(
-					Not(Equal(".bar", literal.String("foo"))),
-					Equal(".", literal.String("foo")),
-					Like(".boo", "abcd"),
-					Like(".boo", "*bcd"),
-				)),
-			),
-		},
-		{
-			path: "jsonrpc,foo,bar",
-			expected: MustConstruct(
-				All(".jsonrpc.foo", Or(
-					Not(Equal(".bar", literal.String("foo"))),
-				)),
-			),
-		},
-		{
-			path: "jsonrpc,foo,boo",
-			expected: MustConstruct(
-				All(".jsonrpc.foo", Or(
-					Like(".boo", "abcd"),
-					Like(".boo", "*bcd"),
-				)),
-			),
-		},
-	} {
-		t.Run(tc.path, func(t *testing.T) {
-			res := pol.Filter(strings.Split(tc.path, ",")...)
-			require.Equal(t, tc.expected.String(), res.String())
-		})
-	}
+	stmt1 := Equal(sel1, basicnode.NewString("value1"))
+	stmt2 := Equal(sel2, basicnode.NewString("value2"))
+
+	p := Policy{stmt1, stmt2}
+
+	filtered := p.Filter(sel1)
+	assert.Len(t, filtered, 1)
+	assert.Equal(t, stmt1, filtered[0])
+
+	filtered = p.Filter(sel2)
+	assert.Len(t, filtered, 1)
+	assert.Equal(t, stmt2, filtered[0])
+
+	sel3 := selector.Selector{selector.NewFieldSegment("nonexistent")}
+	filtered = p.Filter(sel3)
+	assert.Len(t, filtered, 0)
+
+	stmt1 = Equal(
+		selector.Selector{selector.NewFieldSegment(".http.host")},
+		basicnode.NewString("mainnet.infura.io"),
+	)
+	stmt2, err := Like(
+		selector.Selector{selector.NewFieldSegment(".jsonrpc.method")},
+		"eth_*",
+	)
+	require.NoError(t, err)
+
+	p = Policy{stmt1, stmt2}
+	filtered = p.FilterWithMatcher(selector.Selector{selector.NewFieldSegment(".http")}, selector.SegmentStartsWith)
+	assert.Len(t, filtered, 1)
+	assert.Equal(t, stmt1, filtered[0])
+}
+
+func FuzzPolicyFilter(f *testing.F) {
+	f.Add([]byte(`{"selector": [{"field": "http"}], "value": "value1"}`))
+	f.Add([]byte(`{"selector": [{"field": "jsonrpc"}], "value": "value2"}`))
+
+	f.Fuzz(func(t *testing.T, data []byte) {
+		var input struct {
+			Selector []struct {
+				Field string `json:"field"` // because selector.segment is not public
+			} `json:"selector"`
+			Value string `json:"value"`
+		}
+		if err := json.Unmarshal(data, &input); err != nil {
+			t.Skip()
+		}
+
+		var sel selector.Selector
+		for _, seg := range input.Selector {
+			sel = append(sel, selector.NewFieldSegment(seg.Field))
+		}
+		stmt := Equal(sel, basicnode.NewString(input.Value))
+
+		// create a policy and filter it based on the fuzzy input selector
+		p := Policy{stmt}
+		filtered := p.Filter(sel)
+
+		// verify that the filtered policy contains the statement
+		if len(filtered) != 1 || !reflect.DeepEqual(filtered[0], stmt) {
+			t.Errorf("filtered policy does not contain the expected statement")
+		}
+	})
+}
+
+func BenchmarkPolicyFilter(b *testing.B) {
+	sel1 := selector.Selector{selector.NewFieldSegment("http")}
+	sel2 := selector.Selector{selector.NewFieldSegment("jsonrpc")}
+
+	stmt1 := Equal(sel1, basicnode.NewString("value1"))
+	stmt2 := Equal(sel2, basicnode.NewString("value2"))
+
+	p := Policy{stmt1, stmt2}
+
+	b.Run("Filter by sel1", func(b *testing.B) {
+		for i := 0; i < b.N; i++ {
+			p.Filter(sel1)
+		}
+	})
+
+	b.Run("Filter by sel2", func(b *testing.B) {
+		for i := 0; i < b.N; i++ {
+			p.Filter(sel2)
+		}
+	})
+
+	sel3 := selector.Selector{selector.NewFieldSegment("nonexistent")}
+	b.Run("Filter by sel3", func(b *testing.B) {
+		for i := 0; i < b.N; i++ {
+			p.Filter(sel3)
+		}
+	})
 }
--- a/pkg/policy/policy.go
+++ b/pkg/policy/policy.go
@@ -3,13 +3,9 @@ package policy
 // https://github.com/ucan-wg/delegation/blob/4094d5878b58f5d35055a3b93fccda0b8329ebae/README.md#policy

 import (
-	"fmt"
-	"strings"
-
 	"github.com/ipld/go-ipld-prime"
-	"github.com/ipld/go-ipld-prime/codec/dagjson"

-	selpkg "github.com/ucan-wg/go-ucan/pkg/policy/selector"
+	"github.com/ucan-wg/go-ucan/pkg/policy/selector"
 )

 const (
@@ -28,43 +24,14 @@ const (

 type Policy []Statement

-type Constructor func() (Statement, error)
-
-func Construct(cstors ...Constructor) (Policy, error) {
-	stmts, err := assemble(cstors)
-	if err != nil {
-		return nil, err
-	}
-	return stmts, nil
-}
-
-func MustConstruct(cstors ...Constructor) Policy {
-	pol, err := Construct(cstors...)
-	if err != nil {
-		panic(err)
-	}
-	return pol
-}
-
-func (p Policy) String() string {
-	if len(p) == 0 {
-		return "[]"
-	}
-	childs := make([]string, len(p))
-	for i, statement := range p {
-		childs[i] = strings.ReplaceAll(statement.String(), "\n", "\n  ")
-	}
-	return fmt.Sprintf("[\n  %s\n]", strings.Join(childs, ",\n  "))
-}
-
 type Statement interface {
 	Kind() string
-	String() string
+	Selector() selector.Selector
 }

 type equality struct {
 	kind     string
-	selector selpkg.Selector
+	selector selector.Selector
 	value    ipld.Node
 }

@@ -72,47 +39,28 @@ func (e equality) Kind() string {
 	return e.kind
 }

-func (e equality) String() string {
-	child, err := ipld.Encode(e.value, dagjson.Encode)
-	if err != nil {
-		return "ERROR: INVALID VALUE"
-	}
-	return fmt.Sprintf(`["%s", "%s", %s]`, e.kind, e.selector, strings.ReplaceAll(string(child), "\n", "\n  "))
+func (e equality) Selector() selector.Selector {
+	return e.selector
 }

-func Equal(selector string, value ipld.Node) Constructor {
-	return func() (Statement, error) {
-		sel, err := selpkg.Parse(selector)
-		return equality{kind: KindEqual, selector: sel, value: value}, err
-	}
+func Equal(selector selector.Selector, value ipld.Node) Statement {
+	return equality{kind: KindEqual, selector: selector, value: value}
 }

-func GreaterThan(selector string, value ipld.Node) Constructor {
-	return func() (Statement, error) {
-		sel, err := selpkg.Parse(selector)
-		return equality{kind: KindGreaterThan, selector: sel, value: value}, err
-	}
+func GreaterThan(selector selector.Selector, value ipld.Node) Statement {
+	return equality{kind: KindGreaterThan, selector: selector, value: value}
 }

-func GreaterThanOrEqual(selector string, value ipld.Node) Constructor {
-	return func() (Statement, error) {
-		sel, err := selpkg.Parse(selector)
-		return equality{kind: KindGreaterThanOrEqual, selector: sel, value: value}, err
-	}
+func GreaterThanOrEqual(selector selector.Selector, value ipld.Node) Statement {
+	return equality{kind: KindGreaterThanOrEqual, selector: selector, value: value}
 }

-func LessThan(selector string, value ipld.Node) Constructor {
-	return func() (Statement, error) {
-		sel, err := selpkg.Parse(selector)
-		return equality{kind: KindLessThan, selector: sel, value: value}, err
-	}
+func LessThan(selector selector.Selector, value ipld.Node) Statement {
+	return equality{kind: KindLessThan, selector: selector, value: value}
 }

-func LessThanOrEqual(selector string, value ipld.Node) Constructor {
-	return func() (Statement, error) {
-		sel, err := selpkg.Parse(selector)
-		return equality{kind: KindLessThanOrEqual, selector: sel, value: value}, err
-	}
+func LessThanOrEqual(selector selector.Selector, value ipld.Node) Statement {
+	return equality{kind: KindLessThanOrEqual, selector: selector, value: value}
 }

 type negation struct {
@@ -123,16 +71,12 @@ func (n negation) Kind() string {
 	return KindNot
 }

-func (n negation) String() string {
-	child := n.statement.String()
-	return fmt.Sprintf(`["%s", "%s"]`, n.Kind(), strings.ReplaceAll(child, "\n", "\n  "))
+func (n negation) Selector() selector.Selector {
+	return n.statement.Selector()
 }

-func Not(cstor Constructor) Constructor {
-	return func() (Statement, error) {
-		stmt, err := cstor()
-		return negation{statement: stmt}, err
-	}
+func Not(stmt Statement) Statement {
+	return negation{statement: stmt}
 }

 type connective struct {
@@ -144,36 +88,25 @@ func (c connective) Kind() string {
 	return c.kind
 }

-func (c connective) String() string {
-	childs := make([]string, len(c.statements))
-	for i, statement := range c.statements {
-		childs[i] = strings.ReplaceAll(statement.String(), "\n", "\n  ")
+func (c connective) Selector() selector.Selector {
+	// assuming the first statement's selector is representative
+	if len(c.statements) > 0 {
+		return c.statements[0].Selector()
 	}
-	return fmt.Sprintf("[\"%s\", [\n  %s]]\n", c.kind, strings.Join(childs, ",\n  "))
+
+	return selector.Selector{}
 }

-func And(cstors ...Constructor) Constructor {
-	return func() (Statement, error) {
-		stmts, err := assemble(cstors)
-		if err != nil {
-			return nil, err
-		}
-		return connective{kind: KindAnd, statements: stmts}, nil
-	}
+func And(stmts ...Statement) Statement {
+	return connective{kind: KindAnd, statements: stmts}
 }

-func Or(cstors ...Constructor) Constructor {
-	return func() (Statement, error) {
-		stmts, err := assemble(cstors)
-		if err != nil {
-			return nil, err
-		}
-		return connective{kind: KindOr, statements: stmts}, nil
-	}
+func Or(stmts ...Statement) Statement {
+	return connective{kind: KindOr, statements: stmts}
 }

 type wildcard struct {
-	selector selpkg.Selector
+	selector selector.Selector
 	pattern  glob
 }

@@ -181,24 +114,22 @@ func (n wildcard) Kind() string {
 	return KindLike
 }

-func (n wildcard) String() string {
-	return fmt.Sprintf(`["%s", "%s", "%s"]`, n.Kind(), n.selector, n.pattern)
+func (n wildcard) Selector() selector.Selector {
+	return n.selector
 }

-func Like(selector string, pattern string) Constructor {
-	return func() (Statement, error) {
-		g, err := parseGlob(pattern)
-		if err != nil {
-			return nil, err
-		}
-		sel, err := selpkg.Parse(selector)
-		return wildcard{selector: sel, pattern: g}, err
+func Like(selector selector.Selector, pattern string) (Statement, error) {
+	g, err := parseGlob(pattern)
+	if err != nil {
+		return nil, err
 	}
+
+	return wildcard{selector: selector, pattern: g}, nil
 }

 type quantifier struct {
 	kind      string
-	selector  selpkg.Selector
+	selector  selector.Selector
 	statement Statement
 }

@@ -206,41 +137,14 @@ func (n quantifier) Kind() string {
 	return n.kind
 }

-func (n quantifier) String() string {
-	child := n.statement.String()
-	return fmt.Sprintf("[\"%s\", \"%s\",\n  %s]", n.Kind(), n.selector, strings.ReplaceAll(child, "\n", "\n  "))
+func (n quantifier) Selector() selector.Selector {
+	return n.selector
 }

-func All(selector string, cstor Constructor) Constructor {
-	return func() (Statement, error) {
-		stmt, err := cstor()
-		if err != nil {
-			return nil, err
-		}
-		sel, err := selpkg.Parse(selector)
-		return quantifier{kind: KindAll, selector: sel, statement: stmt}, err
-	}
+func All(selector selector.Selector, statement Statement) Statement {
+	return quantifier{kind: KindAll, selector: selector, statement: statement}
 }

-func Any(selector string, cstor Constructor) Constructor {
-	return func() (Statement, error) {
-		stmt, err := cstor()
-		if err != nil {
-			return nil, err
-		}
-		sel, err := selpkg.Parse(selector)
-		return quantifier{kind: KindAny, selector: sel, statement: stmt}, err
-	}
-}
-
-func assemble(cstors []Constructor) ([]Statement, error) {
-	stmts := make([]Statement, 0, len(cstors))
-	for _, cstor := range cstors {
-		stmt, err := cstor()
-		if err != nil {
-			return nil, err
-		}
-		stmts = append(stmts, stmt)
-	}
-	return stmts, nil
+func Any(selector selector.Selector, statement Statement) Statement {
+	return quantifier{kind: KindAny, selector: selector, statement: statement}
 }
--- a/pkg/policy/policy_test.go
+++ b/pkg/policy/policy_test.go
@@ -1,60 +0,0 @@
-package policy_test
-
-import (
-	"fmt"
-	"testing"
-
-	"github.com/stretchr/testify/require"
-
-	"github.com/ucan-wg/go-ucan/pkg/policy"
-	"github.com/ucan-wg/go-ucan/pkg/policy/literal"
-)
-
-func ExamplePolicy() {
-	pol := policy.MustConstruct(
-		policy.Equal(".status", literal.String("draft")),
-		policy.All(".reviewer",
-			policy.Like(".email", "*@example.com"),
-		),
-		policy.Any(".tags", policy.Or(
-			policy.Equal(".", literal.String("news")),
-			policy.Equal(".", literal.String("press")),
-		)),
-	)
-
-	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")),
-		policy.All(".reviewer",
-			policy.Like(".email", "*@example.com"),
-		),
-	)
-	require.NoError(t, err)
-	require.NotNil(t, pol)
-
-	// check if errors cascade correctly
-	pol, err = policy.Construct(
-		policy.Equal(".status", literal.String("draft")),
-		policy.All(".reviewer", policy.Or(
-			policy.Like(".email", "*@example.com"),
-			policy.Like(".", "\\"), // invalid pattern
-		)),
-	)
-	require.Error(t, err)
-	require.Nil(t, pol)
-}
--- a/pkg/policy/selector/parsing.go
+++ b/pkg/policy/selector/parsing.go
@@ -2,18 +2,10 @@ package selector

 import (
 	"fmt"
-	"regexp"
 	"strconv"
 	"strings"
 )

-var (
-	identity   = Selector{segment{str: ".", identity: true}}
-	indexRegex = regexp.MustCompile(`^-?\d+$`)
-	sliceRegex = regexp.MustCompile(`^((\-?\d+:\-?\d*)|(\-?\d*:\-?\d+))$`)
-	fieldRegex = regexp.MustCompile(`^\.[a-zA-Z_]*?$`)
-)
-
 func Parse(str string) (Selector, error) {
 	if len(str) == 0 {
 		return nil, newParseError("empty selector", str, 0, "")
@@ -21,9 +13,6 @@ func Parse(str string) (Selector, error) {
 	if string(str[0]) != "." {
 		return nil, newParseError("selector must start with identity segment '.'", str, 0, string(str[0]))
 	}
-	if str == "." {
-		return identity, nil
-	}

 	col := 0
 	var sel Selector
@@ -38,9 +27,9 @@ func Parse(str string) (Selector, error) {
 			if len(sel) > 0 && sel[len(sel)-1].Identity() {
 				return nil, newParseError("selector contains unsupported recursive descent segment: '..'", str, col, tok)
 			}
-			sel = append(sel, segment{str: ".", identity: true})
+			sel = append(sel, Identity)
 		case "[]":
-			sel = append(sel, segment{str: tok, optional: opt, iterator: true})
+			sel = append(sel, segment{tok, false, opt, true, nil, "", 0})
 		default:
 			if strings.HasPrefix(seg, "[") && strings.HasSuffix(seg, "]") {
 				lookup := seg[1 : len(seg)-1]
--- a/pkg/policy/selector/selector.go
+++ b/pkg/policy/selector/selector.go
@@ -2,6 +2,7 @@ package selector

 import (
 	"fmt"
+	"regexp"
 	"strings"

 	"github.com/ipld/go-ipld-prime"
@@ -14,18 +15,6 @@ import (
 // https://github.com/ucan-wg/delegation/blob/4094d5878b58f5d35055a3b93fccda0b8329ebae/README.md#selectors
 type Selector []segment

-// Select perform the selection described by the selector on the input IPLD DAG.
-// If no error, Select returns either one ipld.Node or a []ipld.Node.
-func (s Selector) Select(subject ipld.Node) (ipld.Node, []ipld.Node, error) {
-	return resolve(s, subject, nil)
-}
-
-// MatchPath tells if the selector operates on the given (string only) path segments.
-// It returns the segments that didn't get consumed by the matching.
-func (s Selector) MatchPath(pathSegment ...string) (bool, []string) {
-	return matchPath(s, pathSegment)
-}
-
 func (s Selector) String() string {
 	var res strings.Builder
 	for _, seg := range s {
@@ -34,6 +23,29 @@ func (s Selector) String() string {
 	return res.String()
 }

+// Matches checks if the selector matches another selector.
+func (s Selector) Matches(other Selector, matcher SegmentMatcher) bool {
+	if len(s) != len(other) {
+		return false
+	}
+
+	for i, seg := range s {
+		if !matcher(seg, other[i]) {
+			return false
+		}
+	}
+
+	return true
+}
+
+var Identity = segment{".", true, false, false, nil, "", 0}
+
+var (
+	indexRegex = regexp.MustCompile(`^-?\d+$`)
+	sliceRegex = regexp.MustCompile(`^((\-?\d+:\-?\d*)|(\-?\d*:\-?\d+))$`)
+	fieldRegex = regexp.MustCompile(`^\.[a-zA-Z_]*?$`)
+)
+
 type segment struct {
 	str      string
 	identity bool
@@ -44,6 +56,48 @@ type segment struct {
 	index    int
 }

+// NewFieldSegment creates a new segment for a field.
+func NewFieldSegment(field string) segment {
+	return segment{
+		str:   fmt.Sprintf(".%s", field),
+		field: field,
+	}
+}
+
+// NewIndexSegment creates a new segment for an index.
+func NewIndexSegment(index int) segment {
+	return segment{
+		str:   fmt.Sprintf("[%d]", index),
+		index: index,
+	}
+}
+
+// NewSliceSegment creates a new segment for a slice.
+func NewSliceSegment(slice []int) segment {
+	return segment{
+		str:   fmt.Sprintf("[%d:%d]", slice[0], slice[1]),
+		slice: slice,
+	}
+}
+
+// NewIteratorSegment creates a new segment for an iterator.
+func NewIteratorSegment() segment {
+	return segment{
+		str:      "*",
+		iterator: true,
+	}
+}
+
+type SegmentMatcher func(s1, s2 segment) bool
+
+var SegmentEquals SegmentMatcher = func(s1, s2 segment) bool {
+	return s1.str == s2.str
+}
+
+var SegmentStartsWith SegmentMatcher = func(s1, s2 segment) bool {
+	return strings.HasPrefix(s1.str, s2.str)
+}
+
 // String returns the segment's string representation.
 func (s segment) String() string {
 	return s.str
@@ -79,6 +133,12 @@ func (s segment) Index() int {
 	return s.index
 }

+// Select uses a selector to extract an IPLD node or set of nodes from the
+// passed subject node.
+func Select(sel Selector, subject ipld.Node) (ipld.Node, []ipld.Node, error) {
+	return resolve(sel, subject, nil)
+}
+
 func resolve(sel Selector, subject ipld.Node, at []string) (ipld.Node, []ipld.Node, error) {
 	cur := subject
 	for i, seg := range sel {
@@ -315,7 +375,7 @@ func resolve(sel Selector, subject ipld.Node, at []string) (ipld.Node, []ipld.No
 				}
 			}

-		default: // Index()
+		default:
 			at = append(at, fmt.Sprintf("%d", seg.Index()))
 			if cur == nil {
 				if seg.Optional() {
@@ -377,39 +437,6 @@ func resolve(sel Selector, subject ipld.Node, at []string) (ipld.Node, []ipld.No
 	return cur, nil, nil
 }

-func matchPath(sel Selector, path []string) (bool, []string) {
-	for _, seg := range sel {
-		if len(path) == 0 {
-			return true, path
-		}
-		switch {
-		case seg.Identity():
-			continue
-
-		case seg.Iterator():
-			// we have reached a [] iterator, it should have matched earlier
-			return false, nil
-
-		case seg.Field() != "":
-			// if exact match on the segment, we continue
-			if path[0] == seg.Field() {
-				path = path[1:]
-				continue
-			}
-			return false, nil
-
-		case seg.Slice() != nil:
-			// we have reached a [<int>:<int>] slicing, it should have matched earlier
-			return false, nil
-
-		default: // Index()
-			// we have reached a [<int>] indexing, it should have matched earlier
-			return false, nil
-		}
-	}
-	return true, path
-}
-
 // resolveSliceIndices resolves the start and end indices for slicing a list or byte array.
 //
 // It takes the slice indices from the selector segment and the length of the list or byte array,
--- a/pkg/policy/selector/selector_test.go
+++ b/pkg/policy/selector/selector_test.go
@@ -313,7 +313,7 @@ func TestSelect(t *testing.T) {
 		sel, err := Parse(".")
 		require.NoError(t, err)

-		one, many, err := sel.Select(anode)
+		one, many, err := Select(sel, anode)
 		require.NoError(t, err)
 		require.NotEmpty(t, one)
 		require.Empty(t, many)
@@ -328,7 +328,7 @@ func TestSelect(t *testing.T) {
 		sel, err := Parse(".name.first")
 		require.NoError(t, err)

-		one, many, err := sel.Select(anode)
+		one, many, err := Select(sel, anode)
 		require.NoError(t, err)
 		require.NotEmpty(t, one)
 		require.Empty(t, many)
@@ -338,7 +338,7 @@ func TestSelect(t *testing.T) {
 		name := must.String(one)
 		require.Equal(t, alice.Name.First, name)

-		one, many, err = sel.Select(bnode)
+		one, many, err = Select(sel, bnode)
 		require.NoError(t, err)
 		require.NotEmpty(t, one)
 		require.Empty(t, many)
@@ -353,7 +353,7 @@ func TestSelect(t *testing.T) {
 		sel, err := Parse(".name.middle?")
 		require.NoError(t, err)

-		one, many, err := sel.Select(anode)
+		one, many, err := Select(sel, anode)
 		require.NoError(t, err)
 		require.NotEmpty(t, one)
 		require.Empty(t, many)
@@ -363,7 +363,7 @@ func TestSelect(t *testing.T) {
 		name := must.String(one)
 		require.Equal(t, *alice.Name.Middle, name)

-		one, many, err = sel.Select(bnode)
+		one, many, err = Select(sel, bnode)
 		require.NoError(t, err)
 		require.Empty(t, one)
 		require.Empty(t, many)
@@ -373,7 +373,7 @@ func TestSelect(t *testing.T) {
 		sel, err := Parse(".name.foo")
 		require.NoError(t, err)

-		one, many, err := sel.Select(anode)
+		one, many, err := Select(sel, anode)
 		require.Error(t, err)
 		require.Empty(t, one)
 		require.Empty(t, many)
@@ -387,7 +387,7 @@ func TestSelect(t *testing.T) {
 		sel, err := Parse(".name.foo?")
 		require.NoError(t, err)

-		one, many, err := sel.Select(anode)
+		one, many, err := Select(sel, anode)
 		require.NoError(t, err)
 		require.Empty(t, one)
 		require.Empty(t, many)
@@ -397,7 +397,7 @@ func TestSelect(t *testing.T) {
 		sel, err := Parse(".interests[]")
 		require.NoError(t, err)

-		one, many, err := sel.Select(anode)
+		one, many, err := Select(sel, anode)
 		require.NoError(t, err)
 		require.Empty(t, one)
 		require.NotEmpty(t, many)
@@ -417,7 +417,7 @@ func TestSelect(t *testing.T) {
 		sel, err := Parse(".interests[0][]")
 		require.NoError(t, err)

-		one, many, err := sel.Select(anode)
+		one, many, err := Select(sel, anode)
 		require.NoError(t, err)
 		require.Empty(t, one)
 		require.NotEmpty(t, many)
@@ -431,32 +431,6 @@ func TestSelect(t *testing.T) {
 	})
 }

-func TestMatch(t *testing.T) {
-	for _, tc := range []struct {
-		sel       string
-		path      []string
-		want      bool
-		remaining []string
-	}{
-		{sel: ".foo.bar", path: []string{"foo", "bar"}, want: true, remaining: []string{}},
-		{sel: ".foo.bar", path: []string{"foo"}, want: true, remaining: []string{}},
-		{sel: ".foo.bar", path: []string{"foo", "bar", "baz"}, want: true, remaining: []string{"baz"}},
-		{sel: ".foo.bar", path: []string{"foo", "faa"}, want: false},
-		{sel: ".foo.[]", path: []string{"foo", "faa"}, want: false},
-		{sel: ".foo.[]", path: []string{"foo"}, want: true, remaining: []string{}},
-		{sel: ".foo.bar?", path: []string{"foo"}, want: true, remaining: []string{}},
-		{sel: ".foo.bar?", path: []string{"foo", "bar"}, want: true, remaining: []string{}},
-		{sel: ".foo.bar?", path: []string{"foo", "baz"}, want: false},
-	} {
-		t.Run(tc.sel, func(t *testing.T) {
-			sel := MustParse(tc.sel)
-			res, remain := sel.MatchPath(tc.path...)
-			require.Equal(t, tc.want, res)
-			require.EqualValues(t, tc.remaining, remain)
-		})
-	}
-}
-
 func FuzzParse(f *testing.F) {
 	selectorCorpus := []string{
 		`.`, `.[]`, `.[]?`, `.[][]?`, `.x`, `.["x"]`, `.[0]`, `.[-1]`, `.[0]`,
@@ -520,6 +494,6 @@ func FuzzParseAndSelect(f *testing.F) {
 		}

 		// look for panic()
-		_, _, _ = sel.Select(node)
+		_, _, _ = Select(sel, node)
 	})
 }
--- a/pkg/policy/selector/supported_test.go
+++ b/pkg/policy/selector/supported_test.go
@@ -52,7 +52,7 @@ func TestSupportedForms(t *testing.T) {
 			require.NoError(t, err)

 			// attempt to select
-			node, nodes, err := sel.Select(makeNode(t, tc.Input))
+			node, nodes, err := selector.Select(sel, makeNode(t, tc.Input))
 			require.NoError(t, err)
 			require.NotEqual(t, node != nil, len(nodes) > 0) // XOR (only one of node or nodes should be set)

@@ -97,7 +97,7 @@ func TestSupportedForms(t *testing.T) {
 			require.NoError(t, err)

 			// attempt to select
-			node, nodes, err := sel.Select(makeNode(t, tc.Input))
+			node, nodes, err := selector.Select(sel, makeNode(t, tc.Input))
 			require.NoError(t, err)
 			// TODO: should Select return a single node which is sometimes a list or null?
 			// require.Equal(t, datamodel.Null, node)
@@ -124,7 +124,7 @@ func TestSupportedForms(t *testing.T) {
 			require.NoError(t, err)

 			// attempt to select
-			node, nodes, err := sel.Select(makeNode(t, tc.Input))
+			node, nodes, err := selector.Select(sel, makeNode(t, tc.Input))
 			require.Error(t, err)
 			assert.Nil(t, node)
 			assert.Empty(t, nodes)
--- a/token/delegation/examples_test.go
+++ b/token/delegation/examples_test.go
@@ -1,331 +0,0 @@
-package delegation_test
-
-import (
-	"bytes"
-	"crypto/rand"
-	"encoding/base64"
-	"encoding/hex"
-	"encoding/json"
-	"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/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/policy"
-	"github.com/ucan-wg/go-ucan/pkg/policy/literal"
-	"github.com/ucan-wg/go-ucan/token/delegation"
-	"github.com/ucan-wg/go-ucan/token/internal/envelope"
-)
-
-// 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)
-
-	// The command defines the shape of the arguments that will be evaluated against the policy
-	cmd := command.MustParse("/foo/bar")
-
-	// The policy defines what is allowed to do.
-	pol := policy.MustConstruct(
-		policy.Equal(".status", literal.String("draft")),
-		policy.All(".reviewer",
-			policy.Like(".email", "*@example.com"),
-		),
-		policy.Any(".tags", policy.Or(
-			policy.Equal(".", literal.String("news")),
-			policy.Equal(".", literal.String("press")),
-		)),
-	)
-
-	tkn, err := delegation.New(issPriv, audDid, cmd, pol,
-		delegation.WithSubject(subDid),
-		delegation.WithExpirationIn(time.Hour),
-		delegation.WithNotBeforeIn(time.Minute),
-		delegation.WithMeta("foo", "bar"),
-		delegation.WithMeta("baz", 123),
-	)
-	printThenPanicOnErr(err)
-
-	// "Seal", meaning encode and wrap into a signed envelope.
-	data, id, err := tkn.ToSealed(issPriv)
-	printThenPanicOnErr(err)
-
-	printCIDAndSealed(id, data)
-
-	// Example output:
-	//
-	// issDid: did:key:z6MkhVFznPeR572rTK51UjoTNpnF8cxuWfPm9oBMPr7y8ABe
-	//
-	// CID (base58BTC): zdpuAv6g2eJSc4RJwEpmooGLVK4wJ4CZpnM92tPVYt5jtMoLW
-	//
-	// DAG-CBOR (base64) out: 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
-	//
-	// Converted to DAG-JSON out:
-	// [
-	//	{
-	//		"/": {
-	//			"bytes": "5rvl8uKmDVGvAVSt4m/0MGiXl9dZwljJJ9m2qHCoIB617l26UvMxyH5uvN9hM7ozfVATiq4mLhoGgm9IGnEEAg"
-	//		}
-	//	},
-	//	{
-	//		"h": {
-	//			"/": {
-	//				"bytes": "NO0BcQ"
-	//			}
-	//		},
-	//		"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": [
-	//				[
-	//					"==",
-	//					".status",
-	//					"draft"
-	//				],
-	//				[
-	//					"all",
-	//					".reviewer",
-	//					[
-	//						"like",
-	//						".email",
-	//						"*@example.com"
-	//					]
-	//				],
-	//				[
-	//					"any",
-	//					".tags",
-	//					[
-	//						"or",
-	//						[
-	//							[
-	//								"==",
-	//								".",
-	//								"news"
-	//							],
-	//							[
-	//								"==",
-	//								".",
-	//								"press"
-	//							]
-	//						]
-	//					]
-	//				]
-	//			],
-	//			"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")
-
-	// The policy defines what is allowed to do.
-	pol := policy.MustConstruct(
-		policy.Equal(".status", literal.String("draft")),
-		policy.All(".reviewer",
-			policy.Like(".email", "*@example.com"),
-		),
-		policy.Any(".tags", policy.Or(
-			policy.Equal(".", literal.String("news")),
-			policy.Equal(".", literal.String("press")),
-		)),
-	)
-
-	tkn, err := delegation.Root(issPriv, audDid, cmd, pol,
-		delegation.WithExpirationIn(time.Hour),
-		delegation.WithNotBeforeIn(time.Minute),
-		delegation.WithMeta("foo", "bar"),
-		delegation.WithMeta("baz", 123),
-	)
-	printThenPanicOnErr(err)
-
-	// "Seal", meaning encode and wrap into a signed envelope.
-	data, id, err := tkn.ToSealed(issPriv)
-	printThenPanicOnErr(err)
-
-	printCIDAndSealed(id, data)
-
-	// Example output:
-	//
-	// issDid: did:key:z6MknWJqz17Y4AfsXSJUFKomuBR4GTkViM7kJYutzTMkCyFF
-	//
-	// CID (base58BTC): zdpuAwLojgfvFCbjz2FsKrvN1khDQ9mFGT6b6pxjMfz73Roed
-	//
-	// DAG-CBOR (base64) out: 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
-	//
-	// Converted to DAG-JSON out:
-	// [
-	//	{
-	//		"/": {
-	//			"bytes": "6dBhbhhGE36CW22OxjOEIAqdDmBqCNsAhCRljnBdXd7YrVOUG+bnXGCIwd4dTGgpEdmY06PFIl7IXKXCh/ESBg"
-	//		}
-	//	},
-	//	{
-	//		"h": {
-	//			"/": {
-	//				"bytes": "NO0BcQ"
-	//			}
-	//		},
-	//		"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": {
-	//				"/": {
-	//					"bytes": "JOsjYi1Pq3OIB0La"
-	//				}
-	//			},
-	//			"pol": [
-	//				[
-	//					"==",
-	//					".status",
-	//					"draft"
-	//				],
-	//				[
-	//					"all",
-	//					".reviewer",
-	//					[
-	//						"like",
-	//						".email",
-	//						"*@example.com"
-	//					]
-	//				],
-	//				[
-	//					"any",
-	//					".tags",
-	//					[
-	//						"or",
-	//						[
-	//							[
-	//								"==",
-	//								".",
-	//								"news"
-	//							],
-	//							[
-	//								"==",
-	//								".",
-	//								"press"
-	//							]
-	//						]
-	//					]
-	//				]
-	//			],
-	//			"sub": "did:key:z6MknWJqz17Y4AfsXSJUFKomuBR4GTkViM7kJYutzTMkCyFF"
-	//		}
-	//	}
-	// ]
-}
-
-// The following example demonstrates how to get a delegation.Token from
-// a DAG-CBOR []byte.
-func ExampleToken_FromSealed() {
-	const cborBase64 = "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"
-
-	cborBytes, err := base64.StdEncoding.DecodeString(cborBase64)
-	printThenPanicOnErr(err)
-
-	tkn, c, err := delegation.FromSealed(cborBytes)
-	printThenPanicOnErr(err)
-
-	fmt.Println("CID (base58BTC):", envelope.CIDToBase58BTC(c))
-	fmt.Println("Issuer (iss):", tkn.Issuer().String())
-	fmt.Println("Audience (aud):", tkn.Audience().String())
-	fmt.Println("Subject (sub):", tkn.Subject().String())
-	fmt.Println("Command (cmd):", tkn.Command().String())
-	fmt.Println("Policy (pol):", tkn.Policy().String())
-	fmt.Println("Nonce (nonce):", hex.EncodeToString(tkn.Nonce()))
-	fmt.Println("Meta (meta):", tkn.Meta().String())
-	fmt.Println("NotBefore (nbf):", tkn.NotBefore())
-	fmt.Println("Expiration (exp):", tkn.Expiration())
-
-	// Output:
-	// CID (base58BTC): zdpuAw26pFuvZa2Z9YAtpZZnWN6VmnRFr7Z8LVY5c7RVWoxGY
-	// Issuer (iss): did:key:z6Mkpzn2n3ZGT2VaqMGSQC3tzmzV4TS9S71iFsDXE1WnoNH2
-	// Audience (aud): did:key:z6Mkq5YmbJcTrPExNDi26imrTCpKhepjBFBSHqrBDN2ArPkv
-	// Subject (sub): did:key:z6MktA1uBdCpq4uJBqE9jjMiLyxZBg9a6xgPPKJjMqss6Zc2
-	// Command (cmd): /foo/bar
-	// Policy (pol): [
-	//   ["==", ".status", "draft"],
-	//   ["all", ".reviewer",
-	//     ["like", ".email", "*@example.com"]],
-	//   ["any", ".tags",
-	//     ["or", [
-	//       ["==", ".", "news"],
-	//       ["==", ".", "press"]]]
-	//     ]
-	// ]
-	// Nonce (nonce): 000102030405060708090a0b
-	// Meta (meta): {}
-	// NotBefore (nbf): <nil>
-	// Expiration (exp): <nil>
-}
-
-func printCIDAndSealed(id cid.Cid, data []byte) {
-	fmt.Println("CID (base58BTC):", envelope.CIDToBase58BTC(id))
-	fmt.Println("DAG-CBOR (base64) out:", base64.StdEncoding.EncodeToString(data))
-	fmt.Println("Converted to DAG-JSON out:")
-
-	node, err := ipld.Decode(data, dagcbor.Decode)
-	printThenPanicOnErr(err)
-
-	rawJSON, err := ipld.Encode(node, dagjson.Encode)
-	printThenPanicOnErr(err)
-
-	prettyJSON := &bytes.Buffer{}
-	err = json.Indent(prettyJSON, rawJSON, "", "\t")
-	printThenPanicOnErr(err)
-
-	fmt.Println(prettyJSON.String())
-}
-
-func printThenPanicOnErr(err error) {
-	if err != nil {
-		panic(err)
-	}
-}
--- a/token/inspect.go
+++ b/token/inspect.go
@@ -1,19 +0,0 @@
-package token
-
-import (
-	"github.com/ipld/go-ipld-prime/datamodel"
-
-	"github.com/ucan-wg/go-ucan/token/internal/envelope"
-)
-
-type Info = envelope.Info
-
-// Inspect inspects the given token IPLD representation and extract some envelope facts.
-func Inspect(node datamodel.Node) (Info, error) {
-	return envelope.Inspect(node)
-}
-
-// FindTag inspect the given token IPLD representation and extract the token tag.
-func FindTag(node datamodel.Node) (string, error) {
-	return envelope.FindTag(node)
-}
--- a/token/interface.go
+++ b/token/interface.go
@@ -1,41 +0,0 @@
-package token
-
-import (
-	"io"
-
-	"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.Meta
-}
-
-type Marshaller interface {
-	// ToSealed wraps the token in an envelope, generates the signature, encodes
-	// the result to DAG-CBOR and calculates the CID of the resulting binary data.
-	ToSealed(privKey crypto.PrivKey) ([]byte, cid.Cid, error)
-	// ToSealedWriter is the same as ToSealed but accepts an io.Writer.
-	ToSealedWriter(w io.Writer, privKey crypto.PrivKey) (cid.Cid, error)
-	// Encode marshals a Token to the format specified by the provided codec.Encoder.
-	Encode(privKey crypto.PrivKey, encFn codec.Encoder) ([]byte, error)
-	// EncodeWriter is the same as Encode, but accepts an io.Writer.
-	EncodeWriter(w io.Writer, privKey crypto.PrivKey, encFn codec.Encoder) error
-	// ToDagCbor marshals the Token to the DAG-CBOR format.
-	ToDagCbor(privKey crypto.PrivKey) ([]byte, error)
-	// ToDagCborWriter is the same as ToDagCbor, but it accepts an io.Writer.
-	ToDagCborWriter(w io.Writer, privKey crypto.PrivKey) error
-	// ToDagJson marshals the Token to the DAG-JSON format.
-	ToDagJson(privKey crypto.PrivKey) ([]byte, error)
-	// ToDagJsonWriter is the same as ToDagJson, but it accepts an io.Writer.
-	ToDagJsonWriter(w io.Writer, privKey crypto.PrivKey) error
-}
--- a/token/invocation/invocation.go
+++ b/token/invocation/invocation.go
@@ -1,124 +0,0 @@
-// Package invocation implements the UCAN [invocation] specification with
-// an immutable Token type as well as methods to convert the Token to and
-// from the [envelope]-enclosed, signed and DAG-CBOR-encoded form that
-// should most commonly be used for transport and storage.
-//
-// [envelope]: https://github.com/ucan-wg/spec#envelope
-// [invocation]: https://github.com/ucan-wg/invocation
-package invocation
-
-import (
-	"crypto/rand"
-	"errors"
-	"fmt"
-	"time"
-
-	"github.com/ucan-wg/go-ucan/did"
-	"github.com/ucan-wg/go-ucan/pkg/command"
-	"github.com/ucan-wg/go-ucan/pkg/meta"
-)
-
-// Token is an immutable type that holds the fields of a UCAN invocation.
-type Token struct {
-	// Issuer DID (invoker)
-	issuer did.DID
-	// Audience DID (receiver/executor)
-	audience did.DID
-	// Subject DID (subject being invoked)
-	subject did.DID
-	// The Command to invoke
-	command command.Command
-	// TODO: args
-	// TODO: prf
-	// A unique, random nonce
-	nonce []byte
-	// Arbitrary Metadata
-	meta *meta.Meta
-	// The timestamp at which the Invocation becomes invalid
-	expiration *time.Time
-	// The timestamp at which the Invocation was created
-	invokedAt *time.Time
-	// TODO: cause
-}
-
-// Issuer returns the did.DID representing the Token's issuer.
-func (t *Token) Issuer() did.DID {
-	return t.issuer
-}
-
-// 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
-}
-
-// Meta returns the Token's metadata.
-func (t *Token) Meta() *meta.Meta {
-	return t.meta
-}
-
-// Expiration returns the time at which the Token expires.
-func (t *Token) Expiration() *time.Time {
-	return t.expiration
-}
-
-func (t *Token) validate() error {
-	var errs error
-
-	requiredDID := func(id did.DID, fieldname string) {
-		if !id.Defined() {
-			errs = errors.Join(errs, fmt.Errorf(`a valid did is required for %s: %s`, fieldname, id.String()))
-		}
-	}
-
-	requiredDID(t.issuer, "Issuer")
-
-	// TODO
-
-	if len(t.nonce) < 12 {
-		errs = errors.Join(errs, fmt.Errorf("token nonce too small"))
-	}
-
-	return errs
-}
-
-// 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
-	)
-
-	// TODO
-
-	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
-}
--- a/token/invocation/invocation.ipldsch
+++ b/token/invocation/invocation.ipldsch
@@ -1,23 +0,0 @@
-type DID string
-
-# The Invocation Payload attaches sender, receiver, and provenance to the Task.
-type Payload struct {
-    # Issuer DID (sender)
-    iss DID
-    # Audience DID (receiver)
-    aud DID
-    # Principal that the chain is about (the Subject)
-    sub optional DID
-
-    # The Command to eventually invoke
-    cmd String
-
-    # A unique, random nonce
-    nonce Bytes
-
-    # Arbitrary Metadata
-    meta {String : Any}
-
-    # The timestamp at which the Invocation becomes invalid
-    exp nullable Int
-}
--- a/token/invocation/ipld.go
+++ b/token/invocation/ipld.go
@@ -1,222 +0,0 @@
-package invocation
-
-import (
-	"io"
-
-	"github.com/ipfs/go-cid"
-	"github.com/ipld/go-ipld-prime"
-	"github.com/ipld/go-ipld-prime/codec"
-	"github.com/ipld/go-ipld-prime/codec/dagcbor"
-	"github.com/ipld/go-ipld-prime/codec/dagjson"
-	"github.com/ipld/go-ipld-prime/datamodel"
-	"github.com/libp2p/go-libp2p/core/crypto"
-
-	"github.com/ucan-wg/go-ucan/did"
-	"github.com/ucan-wg/go-ucan/token/internal/envelope"
-)
-
-// ToSealed wraps the invocation token in an envelope, generates the
-// signature, encodes the result to DAG-CBOR and calculates the CID of
-// the resulting binary data.
-func (t *Token) ToSealed(privKey crypto.PrivKey) ([]byte, cid.Cid, error) {
-	data, err := t.ToDagCbor(privKey)
-	if err != nil {
-		return nil, cid.Undef, err
-	}
-
-	id, err := envelope.CIDFromBytes(data)
-	if err != nil {
-		return nil, cid.Undef, err
-	}
-
-	return data, id, nil
-}
-
-// ToSealedWriter is the same as ToSealed but accepts an io.Writer.
-func (t *Token) ToSealedWriter(w io.Writer, privKey crypto.PrivKey) (cid.Cid, error) {
-	cidWriter := envelope.NewCIDWriter(w)
-
-	if err := t.ToDagCborWriter(cidWriter, privKey); err != nil {
-		return cid.Undef, err
-	}
-
-	return cidWriter.CID()
-}
-
-// FromSealed decodes the provided binary data from the DAG-CBOR format,
-// verifies that the envelope's signature is correct based on the public
-// key taken from the issuer (iss) field and calculates the CID of the
-// incoming data.
-func FromSealed(data []byte) (*Token, cid.Cid, error) {
-	tkn, err := FromDagCbor(data)
-	if err != nil {
-		return nil, cid.Undef, err
-	}
-
-	id, err := envelope.CIDFromBytes(data)
-	if err != nil {
-		return nil, cid.Undef, err
-	}
-
-	return tkn, id, nil
-}
-
-// FromSealedReader is the same as Unseal but accepts an io.Reader.
-func FromSealedReader(r io.Reader) (*Token, cid.Cid, error) {
-	cidReader := envelope.NewCIDReader(r)
-
-	tkn, err := FromDagCborReader(cidReader)
-	if err != nil {
-		return nil, cid.Undef, err
-	}
-
-	id, err := cidReader.CID()
-	if err != nil {
-		return nil, cid.Undef, err
-	}
-
-	return tkn, id, nil
-}
-
-// Encode marshals a Token to the format specified by the provided
-// codec.Encoder.
-func (t *Token) Encode(privKey crypto.PrivKey, encFn codec.Encoder) ([]byte, error) {
-	node, err := t.toIPLD(privKey)
-	if err != nil {
-		return nil, err
-	}
-
-	return ipld.Encode(node, encFn)
-}
-
-// EncodeWriter is the same as Encode, but accepts an io.Writer.
-func (t *Token) EncodeWriter(w io.Writer, privKey crypto.PrivKey, encFn codec.Encoder) error {
-	node, err := t.toIPLD(privKey)
-	if err != nil {
-		return err
-	}
-
-	return ipld.EncodeStreaming(w, node, encFn)
-}
-
-// ToDagCbor marshals the Token to the DAG-CBOR format.
-func (t *Token) ToDagCbor(privKey crypto.PrivKey) ([]byte, error) {
-	return t.Encode(privKey, dagcbor.Encode)
-}
-
-// ToDagCborWriter is the same as ToDagCbor, but it accepts an io.Writer.
-func (t *Token) ToDagCborWriter(w io.Writer, privKey crypto.PrivKey) error {
-	return t.EncodeWriter(w, privKey, dagcbor.Encode)
-}
-
-// ToDagJson marshals the Token to the DAG-JSON format.
-func (t *Token) ToDagJson(privKey crypto.PrivKey) ([]byte, error) {
-	return t.Encode(privKey, dagjson.Encode)
-}
-
-// ToDagJsonWriter is the same as ToDagJson, but it accepts an io.Writer.
-func (t *Token) ToDagJsonWriter(w io.Writer, privKey crypto.PrivKey) error {
-	return t.EncodeWriter(w, privKey, dagjson.Encode)
-}
-
-// Decode unmarshals the input data using the format specified by the
-// provided codec.Decoder into a Token.
-//
-// An error is returned if the conversion fails, or if the resulting
-// Token is invalid.
-func Decode(b []byte, decFn codec.Decoder) (*Token, error) {
-	node, err := ipld.Decode(b, decFn)
-	if err != nil {
-		return nil, err
-	}
-	return FromIPLD(node)
-}
-
-// DecodeReader is the same as Decode, but accept an io.Reader.
-func DecodeReader(r io.Reader, decFn codec.Decoder) (*Token, error) {
-	node, err := ipld.DecodeStreaming(r, decFn)
-	if err != nil {
-		return nil, err
-	}
-	return FromIPLD(node)
-}
-
-// FromDagCbor unmarshals the input data into a Token.
-//
-// An error is returned if the conversion fails, or if the resulting
-// Token is invalid.
-func FromDagCbor(data []byte) (*Token, error) {
-	pay, err := envelope.FromDagCbor[*tokenPayloadModel](data)
-	if err != nil {
-		return nil, err
-	}
-
-	tkn, err := tokenFromModel(*pay)
-	if err != nil {
-		return nil, err
-	}
-
-	return tkn, err
-}
-
-// FromDagCborReader is the same as FromDagCbor, but accept an io.Reader.
-func FromDagCborReader(r io.Reader) (*Token, error) {
-	return DecodeReader(r, dagcbor.Decode)
-}
-
-// FromDagJson unmarshals the input data into a Token.
-//
-// An error is returned if the conversion fails, or if the resulting
-// Token is invalid.
-func FromDagJson(data []byte) (*Token, error) {
-	return Decode(data, dagjson.Decode)
-}
-
-// FromDagJsonReader is the same as FromDagJson, but accept an io.Reader.
-func FromDagJsonReader(r io.Reader) (*Token, error) {
-	return DecodeReader(r, dagjson.Decode)
-}
-
-// FromIPLD decode the given IPLD representation into a Token.
-func FromIPLD(node datamodel.Node) (*Token, error) {
-	pay, err := envelope.FromIPLD[*tokenPayloadModel](node)
-	if err != nil {
-		return nil, err
-	}
-
-	tkn, err := tokenFromModel(*pay)
-	if err != nil {
-		return nil, err
-	}
-
-	return tkn, err
-}
-
-func (t *Token) toIPLD(privKey crypto.PrivKey) (datamodel.Node, error) {
-	var sub *string
-
-	if t.subject != did.Undef {
-		s := t.subject.String()
-		sub = &s
-	}
-
-	// TODO
-
-	var exp *int64
-	if t.expiration != nil {
-		u := t.expiration.Unix()
-		exp = &u
-	}
-
-	model := &tokenPayloadModel{
-		Iss:   t.issuer.String(),
-		Aud:   t.audience.String(),
-		Sub:   sub,
-		Cmd:   t.command.String(),
-		Nonce: t.nonce,
-		Meta:  *t.meta,
-		Exp:   exp,
-	}
-
-	return envelope.ToIPLD(privKey, model)
-}
--- a/token/invocation/schema.go
+++ b/token/invocation/schema.go
@@ -1,77 +0,0 @@
-package invocation
-
-import (
-	_ "embed"
-	"fmt"
-	"sync"
-
-	"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/meta"
-	"github.com/ucan-wg/go-ucan/token/internal/envelope"
-)
-
-// [Tag] is the string used as a key within the SigPayload that identifies
-// that the TokenPayload is an invocation.
-//
-// [Tag]: https://github.com/ucan-wg/invocation#type-tag
-const Tag = "ucan/inv@1.0.0-rc.1"
-
-//go:embed invocation.ipldsch
-var schemaBytes []byte
-
-var (
-	once sync.Once
-	ts   *schema.TypeSystem
-	err  error
-)
-
-func mustLoadSchema() *schema.TypeSystem {
-	once.Do(func() {
-		ts, err = ipld.LoadSchemaBytes(schemaBytes)
-	})
-	if err != nil {
-		panic(fmt.Errorf("failed to load IPLD schema: %s", err))
-	}
-	return ts
-}
-
-func payloadType() schema.Type {
-	return mustLoadSchema().TypeByName("Payload")
-}
-
-var _ envelope.Tokener = (*tokenPayloadModel)(nil)
-
-// TODO
-type tokenPayloadModel struct {
-	// Issuer DID (sender)
-	Iss string
-	// Audience DID (receiver)
-	Aud string
-	// Principal that the chain is about (the Subject)
-	// optional: can be nil
-	Sub *string
-
-	// The Command to eventually invoke
-	Cmd string
-
-	// 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
-}
-
-func (e *tokenPayloadModel) Prototype() schema.TypedPrototype {
-	return bindnode.Prototype((*tokenPayloadModel)(nil), payloadType())
-}
-
-func (*tokenPayloadModel) Tag() string {
-	return Tag
-}
--- a/token/read.go
+++ b/token/read.go
@@ -1,125 +0,0 @@
-package token
-
-import (
-	"fmt"
-	"io"
-
-	"github.com/ipfs/go-cid"
-	"github.com/ipld/go-ipld-prime"
-	"github.com/ipld/go-ipld-prime/codec"
-	"github.com/ipld/go-ipld-prime/codec/dagcbor"
-	"github.com/ipld/go-ipld-prime/codec/dagjson"
-	"github.com/ipld/go-ipld-prime/datamodel"
-
-	"github.com/ucan-wg/go-ucan/token/delegation"
-	"github.com/ucan-wg/go-ucan/token/internal/envelope"
-	"github.com/ucan-wg/go-ucan/token/invocation"
-)
-
-// FromSealed decodes an arbitrary token type from the binary data,
-// verifies that the envelope's signature is correct based on the public
-// key taken from the issuer (iss) field and calculates the CID of the
-// incoming data.
-// Supported and returned types are:
-// - delegation.Token
-// - invocation.Token
-func FromSealed(data []byte) (Token, cid.Cid, error) {
-	tkn, err := FromDagCbor(data)
-	if err != nil {
-		return nil, cid.Undef, err
-	}
-
-	id, err := envelope.CIDFromBytes(data)
-	if err != nil {
-		return nil, cid.Undef, err
-	}
-
-	return tkn, id, nil
-}
-
-// FromSealedReader is the same as Unseal but accepts an io.Reader.
-func FromSealedReader(r io.Reader) (Token, cid.Cid, error) {
-	cidReader := envelope.NewCIDReader(r)
-
-	tkn, err := FromDagCborReader(cidReader)
-	if err != nil {
-		return nil, cid.Undef, err
-	}
-
-	id, err := cidReader.CID()
-	if err != nil {
-		return nil, cid.Undef, err
-	}
-
-	return tkn, id, nil
-}
-
-// Decode unmarshals the input data using the format specified by the
-// provided codec.Decoder into an arbitrary UCAN token.
-// An error is returned if the conversion fails, or if the resulting
-// Token is invalid.
-// Supported and returned types are:
-// - delegation.Token
-// - invocation.Token
-func Decode(b []byte, decFn codec.Decoder) (Token, error) {
-	node, err := ipld.Decode(b, decFn)
-	if err != nil {
-		return nil, err
-	}
-	return fromIPLD(node)
-}
-
-// DecodeReader is the same as Decode, but accept an io.Reader.
-func DecodeReader(r io.Reader, decFn codec.Decoder) (Token, error) {
-	node, err := ipld.DecodeStreaming(r, decFn)
-	if err != nil {
-		return nil, err
-	}
-	return fromIPLD(node)
-}
-
-// FromDagCbor unmarshals an arbitrary DagCbor encoded UCAN token.
-// An error is returned if the conversion fails, or if the resulting
-// Token is invalid.
-// Supported and returned types are:
-// - delegation.Token
-// - invocation.Token
-func FromDagCbor(b []byte) (Token, error) {
-	return Decode(b, dagcbor.Decode)
-}
-
-// FromDagCborReader is the same as FromDagCbor, but accept an io.Reader.
-func FromDagCborReader(r io.Reader) (Token, error) {
-	return DecodeReader(r, dagcbor.Decode)
-}
-
-// FromDagCbor unmarshals an arbitrary DagJson encoded UCAN token.
-// An error is returned if the conversion fails, or if the resulting
-// Token is invalid.
-// Supported and returned types are:
-// - delegation.Token
-// - invocation.Token
-func FromDagJson(b []byte) (Token, error) {
-	return Decode(b, dagjson.Decode)
-}
-
-// FromDagJsonReader is the same as FromDagJson, but accept an io.Reader.
-func FromDagJsonReader(r io.Reader) (Token, error) {
-	return DecodeReader(r, dagjson.Decode)
-}
-
-func fromIPLD(node datamodel.Node) (Token, error) {
-	tag, err := envelope.FindTag(node)
-	if err != nil {
-		return nil, err
-	}
-
-	switch tag {
-	case delegation.Tag:
-		return delegation.FromIPLD(node)
-	case invocation.Tag:
-		return invocation.FromIPLD(node)
-	default:
-		return nil, fmt.Errorf(`unknown tag "%s"`, tag)
-	}
-}
--- a/tokens/delegation/delegation.go
+++ b/tokens/delegation/delegation.go
@@ -15,6 +15,7 @@ import (
 	"fmt"
 	"time"

+	"github.com/ipfs/go-cid"
 	"github.com/libp2p/go-libp2p/core/crypto"

 	"github.com/ucan-wg/go-ucan/did"
@@ -43,13 +44,11 @@ type Token struct {
 	notBefore *time.Time
 	// The timestamp at which the Invocation becomes invalid
 	expiration *time.Time
+	// The CID of the Token when enclosed in an Envelope and encoded to DAG-CBOR
+	cid cid.Cid
 }

 // New creates a validated Token from the provided parameters and options.
-//
-// When creating a delegated token, the Issuer's (iss) DID is assembed
-// using the public key associated with the private key sent as the first
-// parameter.
 func New(privKey crypto.PrivKey, aud did.DID, cmd command.Command, pol policy.Policy, opts ...Option) (*Token, error) {
 	iss, err := did.FromPrivKey(privKey)
 	if err != nil {
@@ -64,6 +63,7 @@ func New(privKey crypto.PrivKey, aud did.DID, cmd command.Command, pol policy.Po
 		policy:   pol,
 		meta:     meta.NewMeta(),
 		nonce:    nil,
+		cid:      cid.Undef,
 	}

 	for _, opt := range opts {
@@ -86,12 +86,6 @@ func New(privKey crypto.PrivKey, aud did.DID, cmd command.Command, pol policy.Po
 	return tkn, nil
 }

-// Root creates a validated UCAN delegation Token from the provided
-// parameters and options.
-//
-// 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 {
@@ -152,6 +146,13 @@ func (t *Token) Expiration() *time.Time {
 	return t.expiration
 }

+// CID returns the content identifier of the Token model when enclosed
+// in an Envelope and encoded to DAG-CBOR.
+// Returns cid.Undef if the token has not been serialized or deserialized yet.
+func (t *Token) CID() cid.Cid {
+	return t.cid
+}
+
 func (t *Token) validate() error {
 	var errs error

--- a/tokens/delegation/delegation.ipldsch
+++ b/tokens/delegation/delegation.ipldsch
--- a/tokens/delegation/delegation_test.go
+++ b/tokens/delegation/delegation_test.go
@@ -11,7 +11,7 @@ import (
 	"github.com/ucan-wg/go-ucan/did"
 	"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/tokens/delegation"
 )

 const (
--- a/tokens/delegation/ipld.go
+++ b/tokens/delegation/ipld.go
@@ -12,7 +12,7 @@ import (
 	"github.com/libp2p/go-libp2p/core/crypto"

 	"github.com/ucan-wg/go-ucan/did"
-	"github.com/ucan-wg/go-ucan/token/internal/envelope"
+	"github.com/ucan-wg/go-ucan/tokens/internal/envelope"
 )

 // ToSealed wraps the delegation token in an envelope, generates the
@@ -32,7 +32,7 @@ func (t *Token) ToSealed(privKey crypto.PrivKey) ([]byte, cid.Cid, error) {
 	return data, id, nil
 }

-// ToSealedWriter is the same as ToSealed but accepts an io.Writer.
+// ToSealedWriter is the same as Seal but accepts an io.Writer.
 func (t *Token) ToSealedWriter(w io.Writer, privKey crypto.PrivKey) (cid.Cid, error) {
 	cidWriter := envelope.NewCIDWriter(w)

@@ -47,38 +47,42 @@ func (t *Token) ToSealedWriter(w io.Writer, privKey crypto.PrivKey) (cid.Cid, er
 // verifies that the envelope's signature is correct based on the public
 // key taken from the issuer (iss) field and calculates the CID of the
 // incoming data.
-func FromSealed(data []byte) (*Token, cid.Cid, error) {
+func FromSealed(data []byte) (*Token, error) {
 	tkn, err := FromDagCbor(data)
 	if err != nil {
-		return nil, cid.Undef, err
+		return nil, err
 	}

 	id, err := envelope.CIDFromBytes(data)
 	if err != nil {
-		return nil, cid.Undef, err
+		return nil, err
 	}

-	return tkn, id, nil
+	tkn.cid = id
+
+	return tkn, nil
 }

 // FromSealedReader is the same as Unseal but accepts an io.Reader.
-func FromSealedReader(r io.Reader) (*Token, cid.Cid, error) {
+func FromSealedReader(r io.Reader) (*Token, error) {
 	cidReader := envelope.NewCIDReader(r)

 	tkn, err := FromDagCborReader(cidReader)
 	if err != nil {
-		return nil, cid.Undef, err
+		return nil, err
 	}

 	id, err := cidReader.CID()
 	if err != nil {
-		return nil, cid.Undef, err
+		return nil, err
 	}

-	return tkn, id, nil
+	tkn.cid = id
+
+	return tkn, nil
 }

-// Encode marshals a Token to the format specified by the provided
+// Encode marshals a View to the format specified by the provided
 // codec.Encoder.
 func (t *Token) Encode(privKey crypto.PrivKey, encFn codec.Encoder) ([]byte, error) {
 	node, err := t.toIPLD(privKey)
@@ -89,7 +93,7 @@ func (t *Token) Encode(privKey crypto.PrivKey, encFn codec.Encoder) ([]byte, err
 	return ipld.Encode(node, encFn)
 }

-// EncodeWriter is the same as Encode, but accepts an io.Writer.
+// EncodeWriter is the same as Encode but accepts an io.Writer.
 func (t *Token) EncodeWriter(w io.Writer, privKey crypto.PrivKey, encFn codec.Encoder) error {
 	node, err := t.toIPLD(privKey)
 	if err != nil {
@@ -99,37 +103,37 @@ func (t *Token) EncodeWriter(w io.Writer, privKey crypto.PrivKey, encFn codec.En
 	return ipld.EncodeStreaming(w, node, encFn)
 }

-// ToDagCbor marshals the Token to the DAG-CBOR format.
+// ToDagCbor marshals the View to the DAG-CBOR format.
 func (t *Token) ToDagCbor(privKey crypto.PrivKey) ([]byte, error) {
 	return t.Encode(privKey, dagcbor.Encode)
 }

-// ToDagCborWriter is the same as ToDagCbor, but it accepts an io.Writer.
+// ToDagCborWriter is the same as ToDagCbor but it accepts an io.Writer.
 func (t *Token) ToDagCborWriter(w io.Writer, privKey crypto.PrivKey) error {
 	return t.EncodeWriter(w, privKey, dagcbor.Encode)
 }

-// ToDagJson marshals the Token to the DAG-JSON format.
+// ToDagJson marshals the View to the DAG-JSON format.
 func (t *Token) ToDagJson(privKey crypto.PrivKey) ([]byte, error) {
 	return t.Encode(privKey, dagjson.Encode)
 }

-// ToDagJsonWriter is the same as ToDagJson, but it accepts an io.Writer.
+// ToDagJsonWriter is the same as ToDagJson but it accepts an io.Writer.
 func (t *Token) ToDagJsonWriter(w io.Writer, privKey crypto.PrivKey) error {
 	return t.EncodeWriter(w, privKey, dagjson.Encode)
 }

 // Decode unmarshals the input data using the format specified by the
-// provided codec.Decoder into a Token.
+// provided codec.Decoder into a View.
 //
 // An error is returned if the conversion fails, or if the resulting
-// Token is invalid.
+// View is invalid.
 func Decode(b []byte, decFn codec.Decoder) (*Token, error) {
 	node, err := ipld.Decode(b, decFn)
 	if err != nil {
 		return nil, err
 	}
-	return FromIPLD(node)
+	return fromIPLD(node)
 }

 // DecodeReader is the same as Decode, but accept an io.Reader.
@@ -138,13 +142,13 @@ func DecodeReader(r io.Reader, decFn codec.Decoder) (*Token, error) {
 	if err != nil {
 		return nil, err
 	}
-	return FromIPLD(node)
+	return fromIPLD(node)
 }

-// FromDagCbor unmarshals the input data into a Token.
+// FromDagCbor unmarshals the input data into a View.
 //
 // An error is returned if the conversion fails, or if the resulting
-// Token is invalid.
+// View is invalid.
 func FromDagCbor(data []byte) (*Token, error) {
 	pay, err := envelope.FromDagCbor[*tokenPayloadModel](data)
 	if err != nil {
@@ -164,10 +168,10 @@ func FromDagCborReader(r io.Reader) (*Token, error) {
 	return DecodeReader(r, dagcbor.Decode)
 }

-// FromDagJson unmarshals the input data into a Token.
+// FromDagJson unmarshals the input data into a View.
 //
 // An error is returned if the conversion fails, or if the resulting
-// Token is invalid.
+// View is invalid.
 func FromDagJson(data []byte) (*Token, error) {
 	return Decode(data, dagjson.Decode)
 }
@@ -177,8 +181,7 @@ func FromDagJsonReader(r io.Reader) (*Token, error) {
 	return DecodeReader(r, dagjson.Decode)
 }

-// FromIPLD decode the given IPLD representation into a Token.
-func FromIPLD(node datamodel.Node) (*Token, error) {
+func fromIPLD(node datamodel.Node) (*Token, error) {
 	pay, err := envelope.FromIPLD[*tokenPayloadModel](node)
 	if err != nil {
 		return nil, err
--- a/tokens/delegation/options.go
+++ b/tokens/delegation/options.go
@@ -24,15 +24,6 @@ func WithExpiration(exp time.Time) Option {
 	}
 }

-// WithExpirationIn set's the Token's optional "expiration" field to Now() plus the given duration.
-func WithExpirationIn(exp time.Duration) Option {
-	return func(t *Token) error {
-		expTime := time.Now().Add(exp)
-		t.expiration = &expTime
-		return nil
-	}
-}
-
 // WithMeta adds a key/value pair in the "meta" field.
 //
 // WithMeta can be used multiple times in the same call.
@@ -57,21 +48,11 @@ func WithNotBefore(nbf time.Time) Option {
 	}
 }

-// WithNotBeforeIn set's the Token's optional "notBefore" field to the value
-// of the provided time.Time.
-func WithNotBeforeIn(nbf time.Duration) Option {
-	return func(t *Token) error {
-		nbfTime := time.Now().Add(nbf)
-		t.notBefore = &nbfTime
-		return nil
-	}
-}
-
 // WithSubject sets the Tokens's optional "subject" field to the value of
 // provided did.DID.
 //
 // This Option should only be used with the New constructor - since
-// Subject is a required parameter when creating a Token via the Root
+// Subject is a required parameter when creating a Token via the  Root
 // constructor, any value provided via this Option will be silently
 // overwritten.
 func WithSubject(sub did.DID) Option {
--- a/tokens/delegation/schema.go
+++ b/tokens/delegation/schema.go
@@ -11,7 +11,7 @@ import (
 	"github.com/ipld/go-ipld-prime/schema"

 	"github.com/ucan-wg/go-ucan/pkg/meta"
-	"github.com/ucan-wg/go-ucan/token/internal/envelope"
+	"github.com/ucan-wg/go-ucan/tokens/internal/envelope"
 )

 // [Tag] is the string used as a key within the SigPayload that identifies
--- a/tokens/delegation/schema_test.go
+++ b/tokens/delegation/schema_test.go
@@ -11,8 +11,8 @@ import (
 	"github.com/stretchr/testify/require"
 	"gotest.tools/v3/golden"

-	"github.com/ucan-wg/go-ucan/token/delegation"
-	"github.com/ucan-wg/go-ucan/token/internal/envelope"
+	"github.com/ucan-wg/go-ucan/tokens/delegation"
+	"github.com/ucan-wg/go-ucan/tokens/internal/envelope"
 )

 //go:embed delegation.ipldsch
@@ -39,9 +39,9 @@ func TestSchemaRoundTrip(t *testing.T) {
 		fmt.Println("cborBytes length", len(cborBytes))
 		fmt.Println("cbor", string(cborBytes))

-		p2, c2, err := delegation.FromSealed(cborBytes)
+		p2, err := delegation.FromSealed(cborBytes)
 		require.NoError(t, err)
-		assert.Equal(t, id, c2)
+		assert.Equal(t, id, p2.CID())
 		fmt.Println("read Cbor", p2)

 		readJson, err := p2.ToDagJson(privKey)
@@ -70,9 +70,10 @@ func TestSchemaRoundTrip(t *testing.T) {
 		assert.Equal(t, newCID, envelope.CIDToBase58BTC(id))

 		// buf = bytes.NewBuffer(cborBytes.Bytes())
-		p2, c2, err := delegation.FromSealedReader(cborBytes)
+		p2, err := delegation.FromSealedReader(cborBytes)
 		require.NoError(t, err)
-		assert.Equal(t, envelope.CIDToBase58BTC(id), envelope.CIDToBase58BTC(c2))
+		t.Log(len(p2.CID().Bytes()), p2.CID().Bytes())
+		assert.Equal(t, envelope.CIDToBase58BTC(id), envelope.CIDToBase58BTC(p2.CID()))

 		readJson := &bytes.Buffer{}
 		require.NoError(t, p2.ToDagJsonWriter(readJson, privKey))
@@ -95,7 +96,7 @@ func BenchmarkRoundTrip(b *testing.B) {
 	b.Run("via buffers", func(b *testing.B) {
 		p1, _ := delegation.FromDagJson(delegationJson)
 		cborBytes, _, _ := p1.ToSealed(privKey)
-		p2, _, _ := delegation.FromSealed(cborBytes)
+		p2, _ := delegation.FromSealed(cborBytes)

 		b.ResetTimer()

@@ -116,7 +117,7 @@ func BenchmarkRoundTrip(b *testing.B) {
 		b.Run("Unseal", func(b *testing.B) {
 			b.ReportAllocs()
 			for i := 0; i < b.N; i++ {
-				_, _, _ = delegation.FromSealed(cborBytes)
+				_, _ = delegation.FromSealed(cborBytes)
 			}
 		})

@@ -133,7 +134,7 @@ func BenchmarkRoundTrip(b *testing.B) {
 		cborBuf := &bytes.Buffer{}
 		_, _ = p1.ToSealedWriter(cborBuf, privKey)
 		cborBytes := cborBuf.Bytes()
-		p2, _, _ := delegation.FromSealedReader(bytes.NewReader(cborBytes))
+		p2, _ := delegation.FromSealedReader(bytes.NewReader(cborBytes))

 		b.ResetTimer()

@@ -160,7 +161,7 @@ func BenchmarkRoundTrip(b *testing.B) {
 			reader := bytes.NewReader(cborBytes)
 			for i := 0; i < b.N; i++ {
 				_, _ = reader.Seek(0, 0)
-				_, _, _ = delegation.FromSealedReader(reader)
+				_, _ = delegation.FromSealedReader(reader)
 			}
 		})

--- a/tokens/delegation/testdata/new.dagjson
+++ b/tokens/delegation/testdata/new.dagjson
--- a/tokens/delegation/testdata/root.dagjson
+++ b/tokens/delegation/testdata/root.dagjson
--- a/tokens/internal/envelope/cid.go
+++ b/tokens/internal/envelope/cid.go
--- a/tokens/internal/envelope/cid_test.go
+++ b/tokens/internal/envelope/cid_test.go
@@ -11,7 +11,7 @@ import (
 	"github.com/stretchr/testify/require"
 	"gotest.tools/v3/golden"

-	"github.com/ucan-wg/go-ucan/token/internal/envelope"
+	"github.com/ucan-wg/go-ucan/tokens/internal/envelope"
 )

 func TestCidFromBytes(t *testing.T) {
--- a/tokens/internal/envelope/example_test.go
+++ b/tokens/internal/envelope/example_test.go
@@ -16,9 +16,8 @@ import (
 	"github.com/ipld/go-ipld-prime/schema"
 	"github.com/libp2p/go-libp2p/core/crypto"
 	"github.com/stretchr/testify/require"
+	"github.com/ucan-wg/go-ucan/tokens/internal/envelope"
 	"gotest.tools/v3/golden"
-
-	"github.com/ucan-wg/go-ucan/token/internal/envelope"
 )

 const (
--- a/tokens/internal/envelope/ipld.go
+++ b/tokens/internal/envelope/ipld.go
@@ -27,9 +27,7 @@ package envelope

 import (
 	"errors"
-	"fmt"
 	"io"
-	"strings"

 	"github.com/ipld/go-ipld-prime"
 	"github.com/ipld/go-ipld-prime/codec"
@@ -43,13 +41,10 @@ import (
 	"github.com/libp2p/go-libp2p/core/crypto"

 	"github.com/ucan-wg/go-ucan/did"
-	"github.com/ucan-wg/go-ucan/token/internal/varsig"
+	"github.com/ucan-wg/go-ucan/tokens/internal/varsig"
 )

-const (
-	VarsigHeaderKey = "h"
-	UCANTagPrefix   = "ucan/"
-)
+const varsigHeaderKey = "h"

 // Tokener must be implemented by types that wish to be enclosed in a
 // UCAN Envelope (presumbably one of the UCAN token types).
@@ -94,7 +89,19 @@ func DecodeReader[T Tokener](r io.Reader, decFn codec.Decoder) (T, error) {
 // An error is returned if the conversion fails, or if the resulting
 // Tokener is invalid.
 func FromDagCbor[T Tokener](b []byte) (T, error) {
-	return Decode[T](b, dagcbor.Decode)
+	undef := *new(T)
+
+	node, err := ipld.Decode(b, dagcbor.Decode)
+	if err != nil {
+		return undef, err
+	}
+
+	tkn, err := fromIPLD[T](node)
+	if err != nil {
+		return undef, err
+	}
+
+	return tkn, nil
 }

 // FromDagCborReader is the same as FromDagCbor, but accept an io.Reader.
@@ -120,81 +127,113 @@ func FromDagJsonReader[T Tokener](r io.Reader) (T, error) {
 // An error is returned if the conversion fails, or if the resulting
 // Tokener is invalid.
 func FromIPLD[T Tokener](node datamodel.Node) (T, error) {
-	zero := *new(T)
+	undef := *new(T)

-	info, err := Inspect(node)
+	tkn, err := fromIPLD[T](node)
 	if err != nil {
-		return zero, err
+		return undef, err
 	}

-	if info.Tag != zero.Tag() {
-		return zero, errors.New("data doesn't match the expected type")
+	return tkn, nil
+}
+
+func fromIPLD[T Tokener](node datamodel.Node) (T, error) {
+	undef := *new(T)
+
+	signatureNode, err := node.LookupByIndex(0)
+	if err != nil {
+		return undef, err
+	}
+
+	signature, err := signatureNode.AsBytes()
+	if err != nil {
+		return undef, err
+	}
+
+	sigPayloadNode, err := node.LookupByIndex(1)
+	if err != nil {
+		return undef, err
+	}
+
+	varsigHeaderNode, err := sigPayloadNode.LookupByString(varsigHeaderKey)
+	if err != nil {
+		return undef, err
+	}
+
+	tokenPayloadNode, err := sigPayloadNode.LookupByString(undef.Tag())
+	if err != nil {
+		return undef, err
 	}

 	// This needs to be done before converting this node to its schema
 	// representation (afterwards, the field might be renamed os it's safer
 	// to use the wire name).
-	issuerNode, err := info.tokenPayloadNode.LookupByString("iss")
+	issuerNode, err := tokenPayloadNode.LookupByString("iss")
 	if err != nil {
-		return zero, err
+		return undef, err
 	}

 	// Replaces the datamodel.Node in tokenPayloadNode with a
 	// schema.TypedNode so that we can cast it to a *token.Token after
 	// unwrapping it.
-	nb := zero.Prototype().Representation().NewBuilder()
+	nb := undef.Prototype().Representation().NewBuilder()

-	err = nb.AssignNode(info.tokenPayloadNode)
+	err = nb.AssignNode(tokenPayloadNode)
 	if err != nil {
-		return zero, err
+		return undef, err
 	}

-	tokenPayloadNode := nb.Build()
+	tokenPayloadNode = nb.Build()

 	tokenPayload := bindnode.Unwrap(tokenPayloadNode)
 	if tokenPayload == nil {
-		return zero, errors.New("failed to Unwrap the TokenPayload")
+		return undef, errors.New("failed to Unwrap the TokenPayload")
 	}

 	tkn, ok := tokenPayload.(T)
 	if !ok {
-		return zero, errors.New("failed to assert the TokenPayload type as *token.Token")
+		return undef, errors.New("failed to assert the TokenPayload type as *token.Token")
 	}

 	// Check that the issuer's DID contains a public key with a type that
 	// matches the VarsigHeader and then verify the SigPayload.
 	issuer, err := issuerNode.AsString()
 	if err != nil {
-		return zero, err
+		return undef, err
 	}

 	issuerDID, err := did.Parse(issuer)
 	if err != nil {
-		return zero, err
+		return undef, err
 	}

 	issuerPubKey, err := issuerDID.PubKey()
 	if err != nil {
-		return zero, err
+		return undef, err
 	}

 	issuerVarsigHeader, err := varsig.Encode(issuerPubKey.Type())
 	if err != nil {
-		return zero, err
+		return undef, err
 	}

-	if string(info.VarsigHeader) != string(issuerVarsigHeader) {
-		return zero, errors.New("the VarsigHeader key type doesn't match the issuer's key type")
-	}
-
-	data, err := ipld.Encode(info.sigPayloadNode, dagcbor.Encode)
+	varsigHeader, err := varsigHeaderNode.AsBytes()
 	if err != nil {
-		return zero, err
+		return undef, err
 	}

-	ok, err = issuerPubKey.Verify(data, info.Signature)
+	if string(varsigHeader) != string(issuerVarsigHeader) {
+		return undef, errors.New("the VarsigHeader key type doesn't match the issuer's key type")
+	}
+
+	data, err := ipld.Encode(sigPayloadNode, dagcbor.Encode)
+	if err != nil {
+		return undef, err
+	}
+
+	ok, err = issuerPubKey.Verify(data, signature)
 	if err != nil || !ok {
-		return zero, errors.New("failed to verify the token's signature")
+		return undef, errors.New("failed to verify the token's signature")
 	}

 	return tkn, nil
@@ -254,7 +293,7 @@ func ToIPLD(privKey crypto.PrivKey, token Tokener) (datamodel.Node, error) {
 	}

 	sigPayloadNode, err := qp.BuildMap(basicnode.Prototype.Any, 2, func(ma datamodel.MapAssembler) {
-		qp.MapEntry(ma, VarsigHeaderKey, qp.Bytes(varsigHeader))
+		qp.MapEntry(ma, varsigHeaderKey, qp.Bytes(varsigHeader))
 		qp.MapEntry(ma, token.Tag(), qp.Node(tokenPayloadNode))
 	})

@@ -273,121 +312,3 @@ func ToIPLD(privKey crypto.PrivKey, token Tokener) (datamodel.Node, error) {
 		qp.ListEntry(la, qp.Node(sigPayloadNode))
 	})
 }
-
-// FindTag inspects the given token IPLD representation and extract the token tag.
-func FindTag(node datamodel.Node) (string, error) {
-	sigPayloadNode, err := node.LookupByIndex(1)
-	if err != nil {
-		return "", err
-	}
-
-	if sigPayloadNode.Kind() != datamodel.Kind_Map {
-		return "", fmt.Errorf("unexpected type instead of map")
-	}
-
-	it := sigPayloadNode.MapIterator()
-	i := 0
-
-	for !it.Done() {
-		if i >= 2 {
-			return "", fmt.Errorf("expected two and only two fields in SigPayload")
-		}
-		i++
-
-		k, _, err := it.Next()
-		if err != nil {
-			return "", err
-		}
-
-		key, err := k.AsString()
-		if err != nil {
-			return "", err
-		}
-
-		if strings.HasPrefix(key, UCANTagPrefix) {
-			return key, nil
-		}
-	}
-	return "", fmt.Errorf("no token tag found")
-}
-
-type Info struct {
-	Tag              string
-	Signature        []byte
-	VarsigHeader     []byte
-	sigPayloadNode   datamodel.Node // private, we don't want to expose that
-	tokenPayloadNode datamodel.Node // private, we don't want to expose that
-}
-
-// Inspect inspects the given token IPLD representation and extract some envelope facts.
-func Inspect(node datamodel.Node) (Info, error) {
-	var res Info
-
-	signatureNode, err := node.LookupByIndex(0)
-	if err != nil {
-		return Info{}, err
-	}
-
-	res.Signature, err = signatureNode.AsBytes()
-	if err != nil {
-		return Info{}, err
-	}
-
-	res.sigPayloadNode, err = node.LookupByIndex(1)
-	if err != nil {
-		return Info{}, err
-	}
-
-	if res.sigPayloadNode.Kind() != datamodel.Kind_Map {
-		return Info{}, fmt.Errorf("unexpected type instead of map")
-	}
-
-	it := res.sigPayloadNode.MapIterator()
-	foundVarsigHeader := false
-	foundTokenPayload := false
-	i := 0
-
-	for !it.Done() {
-		if i >= 2 {
-			return Info{}, fmt.Errorf("expected two and only two fields in SigPayload")
-		}
-		i++
-
-		k, v, err := it.Next()
-		if err != nil {
-			return Info{}, err
-		}
-
-		key, err := k.AsString()
-		if err != nil {
-			return Info{}, err
-		}
-
-		switch {
-		case key == VarsigHeaderKey:
-			foundVarsigHeader = true
-			res.VarsigHeader, err = v.AsBytes()
-			if err != nil {
-				return Info{}, err
-			}
-		case strings.HasPrefix(key, UCANTagPrefix):
-			foundTokenPayload = true
-			res.Tag = key
-			res.tokenPayloadNode = v
-		default:
-			return Info{}, fmt.Errorf("unexpected key type %q", key)
-		}
-	}
-
-	if i != 2 {
-		return Info{}, fmt.Errorf("expected two and only two fields in SigPayload: %d", i)
-	}
-	if !foundVarsigHeader {
-		return Info{}, errors.New("failed to find VarsigHeader field")
-	}
-	if !foundTokenPayload {
-		return Info{}, errors.New("failed to find TokenPayload field")
-	}
-
-	return res, nil
-}
--- a/tokens/internal/envelope/ipld_test.go
+++ b/tokens/internal/envelope/ipld_test.go
@@ -3,17 +3,12 @@ package envelope_test
 import (
 	"bytes"
 	"crypto/sha256"
-	"encoding/base64"
-	"os"
 	"testing"

-	"github.com/ipld/go-ipld-prime"
-	"github.com/ipld/go-ipld-prime/codec/dagcbor"
 	"github.com/stretchr/testify/assert"
 	"github.com/stretchr/testify/require"
+	"github.com/ucan-wg/go-ucan/tokens/internal/envelope"
 	"gotest.tools/v3/golden"
-
-	"github.com/ucan-wg/go-ucan/token/internal/envelope"
 )

 func TestDecode(t *testing.T) {
@@ -154,56 +149,3 @@ func TestHash(t *testing.T) {
 	require.Equal(t, hash1[:], hash2)
 	require.Equal(t, hash1[:], hash3)
 }
-
-func TestInspect(t *testing.T) {
-	t.Parallel()
-
-	data := golden.Get(t, "example.dagcbor")
-	node, err := ipld.Decode(data, dagcbor.Decode)
-	require.NoError(t, err)
-
-	expSig, err := base64.RawStdEncoding.DecodeString("fPqfwL3iFpbw9SvBiq0DIbUurv9o6c36R08tC/yslGrJcwV51ghzWahxdetpEf6T5LCszXX9I/K8khvnmAxjAg")
-	require.NoError(t, err)
-
-	info, err := envelope.Inspect(node)
-	require.NoError(t, err)
-	assert.Equal(t, expSig, info.Signature)
-	assert.Equal(t, "ucan/example@v1.0.0-rc.1", info.Tag)
-	assert.Equal(t, []byte{0x34, 0xed, 0x1, 0x71}, info.VarsigHeader)
-}
-
-func FuzzInspect(f *testing.F) {
-	data, err := os.ReadFile("testdata/example.dagcbor")
-	require.NoError(f, err)
-
-	f.Add(data)
-
-	f.Fuzz(func(t *testing.T, data []byte) {
-		node, err := ipld.Decode(data, dagcbor.Decode)
-		if err != nil {
-			t.Skip()
-		}
-		_, err = envelope.Inspect(node)
-		if err != nil {
-			t.Skip()
-		}
-	})
-}
-
-func FuzzFindTag(f *testing.F) {
-	data, err := os.ReadFile("testdata/example.dagcbor")
-	require.NoError(f, err)
-
-	f.Add(data)
-
-	f.Fuzz(func(t *testing.T, data []byte) {
-		node, err := ipld.Decode(data, dagcbor.Decode)
-		if err != nil {
-			t.Skip()
-		}
-		_, err = envelope.FindTag(node)
-		if err != nil {
-			t.Skip()
-		}
-	})
-}
--- a/tokens/internal/envelope/testdata/example.dagcbor
+++ b/tokens/internal/envelope/testdata/example.dagcbor
--- a/tokens/internal/envelope/testdata/example.dagjson
+++ b/tokens/internal/envelope/testdata/example.dagjson
--- a/tokens/internal/envelope/testdata/example.ipldsch
+++ b/tokens/internal/envelope/testdata/example.ipldsch
--- a/tokens/internal/varsig/varsig.go
+++ b/tokens/internal/varsig/varsig.go
--- a/tokens/internal/varsig/varsig_test.go
+++ b/tokens/internal/varsig/varsig_test.go
@@ -8,7 +8,7 @@ import (
 	"github.com/libp2p/go-libp2p/core/crypto/pb"
 	"github.com/stretchr/testify/assert"

-	"github.com/ucan-wg/go-ucan/token/internal/varsig"
+	"github.com/ucan-wg/go-ucan/tokens/internal/varsig"
 )

 func TestDecode(t *testing.T) {
Author	SHA1	Message	Date
Fabio Bozzo	bfd5f00618	Merge branch 'v1' into v1-policy-subset-selection	2024-09-24 19:41:39 +02:00
Fabio Bozzo	d66b8e40ec	versatile segments matchers	2024-09-24 19:36:01 +02:00
Fabio Bozzo	18820f5e9d	refactor policy.Match as receiver	2024-09-24 11:36:31 +02:00
Fabio Bozzo	ddaa67ed7d	feat(policy): filter statements subset by selector	2024-09-24 11:33:06 +02:00