feat: turns out, PayloadEncoding can be multiple values for EIP191

feat(test): add more tests for the presets, and compat with iso-ucan
feat(ecdsa): implement varsig for EdDSA
2025-07-24 16:52:58 +02:00 · 2025-07-24 16:52:58 +02:00 · 2025-07-22 14:24:39 +02:00 · 2025-07-22 13:57:22 +02:00 · 2025-07-22 13:10:12 +02:00 · 2025-07-22 12:04:31 +02:00
18 changed files with 750 additions and 333 deletions
--- a/.github/workflows/pre-commit.yaml
+++ b/.github/workflows/pre-commit.yaml
@@ -1,9 +1,7 @@
 name: pre-commit

 on:
-  pull_request:
  push:
-    # branches: [main]

 jobs:
  pre-commit:
--- a/README.md
+++ b/README.md
@@ -2,12 +2,14 @@

 `go-varsig` implements the upcoming v1.0.0 release of the [`varsig` specification](https://github.com/ChainAgnostic/varsig/pull/18)
 with limited (and soon to be deprecated) support for the `varsig` < v1.0
-specification.  This is predominatly included to support the UCAN v1.0
+specification.  This is predominantly included to support the UCAN v1.0
 use-case.

+Built with ❤️ by [Consensys](https://consensys.io/).
+
 ## Usage

-Include the `go-varsig` library  by running the following command:
+Include the `go-varsig` library by running the following command:

 ```bash
 go get github.com/ucan-wg/go-varsig@latest
@@ -29,7 +31,7 @@ asdf install

 ### Checks

-This repository contains an set of pre-commit hooks that are run prior to
+This repository contains a set of pre-commit hooks that are run prior to
 each `git commit`.  You can also run these checks manually using the
 following command:

@@ -54,3 +56,10 @@ Since there's only one workflow, the simplest command to test it is:
 ```bash
 act
 ```
+
+## License
+
+This project is dual-licensed under Apache 2.0 and MIT terms:
+
+- Apache License, Version 2.0, ([LICENSE-APACHE](https://github.com/ucan-wg/go-varsig/blob/master/LICENSE-APACHE-2.0) or http://www.apache.org/licenses/LICENSE-2.0)
+- MIT license ([LICENSE-MIT](https://github.com/ucan-wg/go-varsig/blob/master/LICENSE-MIT) or http://opensource.org/licenses/MIT)
--- a/common.go
+++ b/common.go
@@ -1,41 +1,73 @@
 package varsig

-// Ed25519 produces a varsig that describes the associated algorithm defined
-// by the [IANA JOSE specification].
-//
+import "fmt"
+
 // [IANA JOSE specification]: https://www.iana.org/assignments/jose/jose.xhtml#web-signature-encryption-algorithms
-func Ed25519(payloadEncoding PayloadEncoding, opts ...Option) (*EdDSAVarsig, error) {
-	return NewEdDSAVarsig(CurveEd25519, HashAlgorithmSHA512, payloadEncoding, opts...)
+
+// Ed25519 produces a varsig for EdDSA using Ed25519 curve.
+// This algorithm is defined in [IANA JOSE specification].
+func Ed25519(payloadEncoding PayloadEncoding, opts ...Option) (EdDSAVarsig, error) {
+	return NewEdDSAVarsig(CurveEd25519, HashSha2_512, payloadEncoding, opts...)
 }

-// Ed448 produces a varsig that describes the associated algorithm defined
-// by the [IANA JOSE specification].
-//
-// [IANA JOSE specification]: https://www.iana.org/assignments/jose/jose.xhtml#web-signature-encryption-algorithms
-func Ed448(payloadEncoding PayloadEncoding, opts ...Option) (*EdDSAVarsig, error) {
-	return NewEdDSAVarsig(CurveEd448, HashAlgorithmShake256, payloadEncoding, opts...)
+// Ed448 produces a varsig for EdDSA using Ed448 curve.
+// This algorithm is defined in [IANA JOSE specification].
+func Ed448(payloadEncoding PayloadEncoding, opts ...Option) (EdDSAVarsig, error) {
+	return NewEdDSAVarsig(CurveEd448, HashShake_256, payloadEncoding, opts...)
 }

-// RS256 produces a varsig that describes the associated algorithm defined
-// by the [IANA JOSE specification].
-//
-// [IANA JOSE specification]: https://www.iana.org/assignments/jose/jose.xhtml#web-signature-encryption-algorithms
-func RS256(keyLength uint64, payloadEncoding PayloadEncoding, opts ...Option) (*RSAVarsig, error) {
-	return NewRSAVarsig(HashAlgorithmSHA256, keyLength, payloadEncoding, opts...)
+// RS256 produces a varsig for RSASSA-PKCS1-v1_5 using SHA-256.
+// This algorithm is defined in [IANA JOSE specification].
+func RS256(keyLength uint64, payloadEncoding PayloadEncoding, opts ...Option) (RSAVarsig, error) {
+	return NewRSAVarsig(HashSha2_256, keyLength, payloadEncoding, opts...)
 }

-// RS384 produces a varsig that describes the associated algorithm defined
-// by the [IANA JOSE specification].
-//
-// [IANA JOSE specification]: https://www.iana.org/assignments/jose/jose.xhtml#web-signature-encryption-algorithms
-func RS384(keyLength uint64, payloadEncoding PayloadEncoding, opts ...Option) (*RSAVarsig, error) {
-	return NewRSAVarsig(HashAlgorithmSHA384, keyLength, payloadEncoding, opts...)
+// RS384 produces a varsig for RSASSA-PKCS1-v1_5 using SHA-384.
+// This algorithm is defined in [IANA JOSE specification].
+func RS384(keyLength uint64, payloadEncoding PayloadEncoding, opts ...Option) (RSAVarsig, error) {
+	return NewRSAVarsig(HashSha2_384, keyLength, payloadEncoding, opts...)
 }

-// RS512 produces a varsig that describes the associated algorithm defined
-// by the [IANA JOSE specification].
-//
-// [IANA JOSE specification]: https://www.iana.org/assignments/jose/jose.xhtml#web-signature-encryption-algorithms
-func RS512(keyLength uint64, payloadEncoding PayloadEncoding, opts ...Option) (*RSAVarsig, error) {
-	return NewRSAVarsig(HashAlgorithmSHA512, keyLength, payloadEncoding, opts...)
+// RS512 produces a varsig for RSASSA-PKCS1-v1_5 using SHA-512.
+// This algorithm is defined in [IANA JOSE specification].
+func RS512(keyLength uint64, payloadEncoding PayloadEncoding, opts ...Option) (RSAVarsig, error) {
+	return NewRSAVarsig(HashSha2_512, keyLength, payloadEncoding, opts...)
+}
+
+// ES256 produces a varsig for ECDSA using P-256 and SHA-256.
+// This algorithm is defined in [IANA JOSE specification].
+func ES256(payloadEncoding PayloadEncoding, opts ...Option) (ECDSAVarsig, error) {
+	return NewECDSAVarsig(CurveP256, HashSha2_256, payloadEncoding, opts...)
+}
+
+// ES256K produces a varsig for ECDSA using secp256k1 curve and SHA-256.
+// This algorithm is defined in [IANA JOSE specification].
+func ES256K(payloadEncoding PayloadEncoding, opts ...Option) (ECDSAVarsig, error) {
+	return NewECDSAVarsig(CurveSecp256k1, HashSha2_256, payloadEncoding, opts...)
+}
+
+// ES384 produces a varsig for ECDSA using P-384 and SHA-384.
+// This algorithm is defined in [IANA JOSE specification].
+func ES384(payloadEncoding PayloadEncoding, opts ...Option) (ECDSAVarsig, error) {
+	return NewECDSAVarsig(CurveP384, HashSha2_384, payloadEncoding, opts...)
+}
+
+// ES512 produces a varsig for ECDSA using P-521 and SHA-512.
+// This algorithm is defined in [IANA JOSE specification].
+func ES512(payloadEncoding PayloadEncoding, opts ...Option) (ECDSAVarsig, error) {
+	return NewECDSAVarsig(CurveP521, HashSha2_512, payloadEncoding, opts...)
+}
+
+// EIP191 produces a varsig for ECDSA using the Secp256k1 curve, Keccak256 and encoded
+// with the "personal_sign" format defined by [EIP191].
+// payloadEncoding must be either PayloadEncodingEIP191Raw or PayloadEncodingEIP191Cbor.
+// [EIP191]: https://eips.ethereum.org/EIPS/eip-191
+func EIP191(payloadEncoding PayloadEncoding, opts ...Option) (ECDSAVarsig, error) {
+	switch payloadEncoding {
+	case PayloadEncodingEIP191Raw, PayloadEncodingEIP191Cbor:
+	default:
+		return ECDSAVarsig{}, fmt.Errorf("%w for EIP191: %v", ErrUnsupportedPayloadEncoding, payloadEncoding)
+	}
+
+	return NewECDSAVarsig(CurveSecp256k1, HashKeccak256, payloadEncoding, opts...)
 }
--- a/common_test.go
+++ b/common_test.go
@@ -1,63 +1,147 @@
 package varsig_test

 import (
+	"encoding/hex"
 	"testing"

-	"github.com/stretchr/testify/assert"
+	"github.com/stretchr/testify/require"

 	"github.com/ucan-wg/go-varsig"
 )

-func TestEd25519(t *testing.T) {
-	t.Parallel()
+func TestRoundTrip(t *testing.T) {
+	for _, tc := range []struct {
+		name      string
+		varsig    varsig.Varsig
+		dataHex   string
+		dataBytes []byte
+	}{
+		// Arbitrary use of presets
+		{
+			name:    "Ed25519",
+			varsig:  must(varsig.Ed25519(varsig.PayloadEncodingDAGCBOR)),
+			dataHex: "3401ed01ed011371",
+		},
+		{
+			name:    "Ed448",
+			varsig:  must(varsig.Ed448(varsig.PayloadEncodingDAGCBOR)),
+			dataHex: "3401ed0183241971",
+		},
+		{
+			name:    "RS256",
+			varsig:  must(varsig.RS256(0x100, varsig.PayloadEncodingDAGCBOR)),
+			dataHex: "3401852412800271",
+		},
+		{
+			name:    "RS384",
+			varsig:  must(varsig.RS384(0x100, varsig.PayloadEncodingDAGCBOR)),
+			dataHex: "3401852420800271",
+		},
+		{
+			name:    "RS512",
+			varsig:  must(varsig.RS512(0x100, varsig.PayloadEncodingDAGCBOR)),
+			dataHex: "3401852413800271",
+		},
+		{
+			name:    "ES256",
+			varsig:  must(varsig.ES256(varsig.PayloadEncodingDAGCBOR)),
+			dataHex: "3401ec0180241271",
+		},
+		{
+			name:    "ES256K",
+			varsig:  must(varsig.ES256K(varsig.PayloadEncodingDAGCBOR)),
+			dataHex: "3401ec01e7011271",
+		},
+		{
+			name:    "ES384",
+			varsig:  must(varsig.ES384(varsig.PayloadEncodingDAGCBOR)),
+			dataHex: "3401ec0181242071",
+		},
+		{
+			name:    "ES512",
+			varsig:  must(varsig.ES512(varsig.PayloadEncodingDAGCBOR)),
+			dataHex: "3401ec0182241371",
+		},
+		{
+			name:    "EIP191",
+			varsig:  must(varsig.EIP191(varsig.PayloadEncodingEIP191Raw)),
+			dataHex: "3401ec01e7011b91c3035f",
+		},

-	in := mustVarsig[varsig.EdDSAVarsig](t)(varsig.Ed25519(varsig.PayloadEncodingDAGCBOR))
-	out := roundTrip(t, in, "3401ed01ed011371")
-	assertEdDSAEqual(t, in, out)
+		// from https://github.com/hugomrdias/iso-repo/blob/main/packages/iso-ucan/test/varsig.test.js
+		{
+			name:      "RS256+RAW",
+			varsig:    must(varsig.RS256(256, varsig.PayloadEncodingVerbatim)),
+			dataBytes: []byte{52, 1, 133, 36, 18, 128, 2, 95},
+		},
+		{
+			name:      "ES256+RAW",
+			varsig:    must(varsig.ES256(varsig.PayloadEncodingVerbatim)),
+			dataBytes: []byte{52, 1, 236, 1, 128, 36, 18, 95},
+		},
+		{
+			name:      "ES512+RAW",
+			varsig:    must(varsig.ES512(varsig.PayloadEncodingVerbatim)),
+			dataBytes: []byte{52, 1, 236, 1, 130, 36, 19, 95},
+		},
+		{
+			name:      "ES256K+RAW",
+			varsig:    must(varsig.ES256K(varsig.PayloadEncodingVerbatim)),
+			dataBytes: []byte{52, 1, 236, 1, 231, 1, 18, 95},
+		},
+		{
+			name:      "EIP191+RAW",
+			varsig:    must(varsig.EIP191(varsig.PayloadEncodingEIP191Raw)),
+			dataBytes: []byte{52, 1, 236, 1, 231, 1, 27, 145, 195, 3, 95},
+		},
+		{
+			name:      "EIP191+DAG-CBOR",
+			varsig:    must(varsig.EIP191(varsig.PayloadEncodingEIP191Cbor)),
+			dataBytes: []byte{52, 1, 236, 1, 231, 1, 27, 145, 195, 3, 113},
+		},
+	} {
+		t.Run(tc.name, func(t *testing.T) {
+			// round-trip encode and back
+			data := tc.varsig.Encode()
+
+			if tc.dataBytes != nil {
+				require.Equal(t, tc.dataBytes, data)
+			}
+			if tc.dataHex != "" {
+				require.Equal(t, tc.dataHex, hex.EncodeToString(data))
+			}
+
+			rt, err := varsig.Decode(data)
+			require.NoError(t, err)
+
+			require.Equal(t, tc.varsig.Version(), rt.Version())
+			require.Equal(t, tc.varsig.Discriminator(), rt.Discriminator())
+			require.Equal(t, tc.varsig.PayloadEncoding(), rt.PayloadEncoding())
+			require.Equal(t, tc.varsig.Signature(), rt.Signature())
+
+			switch vs := tc.varsig.(type) {
+			case varsig.EdDSAVarsig:
+				rt := rt.(varsig.EdDSAVarsig)
+				require.Equal(t, vs.Curve(), rt.Curve())
+				require.Equal(t, vs.Hash(), rt.Hash())
+			case varsig.ECDSAVarsig:
+				rt := rt.(varsig.ECDSAVarsig)
+				require.Equal(t, vs.Curve(), rt.Curve())
+				require.Equal(t, vs.Hash(), rt.Hash())
+			case varsig.RSAVarsig:
+				rt := rt.(varsig.RSAVarsig)
+				require.Equal(t, vs.Hash(), rt.Hash())
+				require.Equal(t, vs.KeyLength(), rt.KeyLength())
+			default:
+				t.Fatalf("unexpected varsig type: %T", vs)
+			}
+		})
+	}
 }

-func TestEd448(t *testing.T) {
-	t.Parallel()
-
-	in := mustVarsig[varsig.EdDSAVarsig](t)(varsig.Ed448(varsig.PayloadEncodingDAGCBOR))
-	out := roundTrip(t, in, "3401ed0183241971")
-	assertEdDSAEqual(t, in, out)
-}
-
-func TestRS256(t *testing.T) {
-	t.Parallel()
-
-	in := mustVarsig[varsig.RSAVarsig](t)(varsig.RS256(0x100, varsig.PayloadEncodingDAGCBOR))
-	out := roundTrip(t, in, "3401852412800271")
-	assertRSAEqual(t, in, out)
-}
-
-func TestRS384(t *testing.T) {
-	t.Parallel()
-
-	in := mustVarsig[varsig.RSAVarsig](t)(varsig.RS384(0x100, varsig.PayloadEncodingDAGCBOR))
-	out := roundTrip(t, in, "3401852420800271")
-	assertRSAEqual(t, in, out)
-}
-
-func TestRS512(t *testing.T) {
-	t.Parallel()
-
-	in := mustVarsig[varsig.RSAVarsig](t)(varsig.RS512(0x100, varsig.PayloadEncodingDAGCBOR))
-	out := roundTrip(t, in, "3401852413800271")
-	assertRSAEqual(t, in, out)
-}
-
-func assertEdDSAEqual(t *testing.T, in, out *varsig.EdDSAVarsig) {
-	t.Helper()
-
-	assert.Equal(t, in.Curve(), out.Curve())
-	assert.Equal(t, in.HashAlgorithm(), out.HashAlgorithm())
-}
-
-func assertRSAEqual(t *testing.T, in, out *varsig.RSAVarsig) {
-	t.Helper()
-
-	assert.Equal(t, in.HashAlgorithm(), out.HashAlgorithm())
-	assert.Equal(t, in.KeyLength(), out.KeyLength())
+func must[T any](v T, err error) T {
+	if err != nil {
+		panic(err)
+	}
+	return v
 }
--- a/constant.go
+++ b/constant.go
@@ -1,122 +1,206 @@
 package varsig

 import (
-	"bytes"
 	"encoding/binary"
 	"fmt"
-
-	"github.com/multiformats/go-multicodec"
 )

-// Prefix is the multicodec.Code for the varsig's varuint prefix byte.
-const Prefix = uint64(multicodec.Varsig)
+// Prefix is the value for the varsig's varuint prefix byte.
+const Prefix = uint64(0x34)

-// HashAlgorithm is the multicodec.Code that specifies the hash algorithm
+// Hash is the value that specifies the hash algorithm
 // that's used to reduce the signed content
-type HashAlgorithm uint64
+type Hash uint64

-// Constant multicodec.Code values that allow Varsig implementations to
-// specify how the payload content is hashed before the signature is
-// generated.
+// Constant values that allow Varsig implementations to specify how
+// the payload content is hashed before the signature is generated.
 const (
-	HashAlgorithmUnspecified HashAlgorithm = 0x00
-	HashAlgorithmSHA256                    = HashAlgorithm(multicodec.Sha2_256)
-	HashAlgorithmSHA384                    = HashAlgorithm(multicodec.Sha2_384)
-	HashAlgorithmSHA512                    = HashAlgorithm(multicodec.Sha2_512)
-	HashAlgorithmShake256                  = HashAlgorithm(multicodec.Shake256)
+	HashUnspecified Hash = 0x00
+
+	HashSha2_224 = Hash(0x1013)
+	HashSha2_256 = Hash(0x12)
+	HashSha2_384 = Hash(0x20)
+	HashSha2_512 = Hash(0x13)
+
+	HashSha3_224 = Hash(0x17)
+	HashSha3_256 = Hash(0x16)
+	HashSha3_384 = Hash(0x15)
+	HashSha3_512 = Hash(0x14)
+
+	HashSha512_224 = Hash(0x1014)
+	HashSha512_256 = Hash(0x1015)
+
+	HashBlake2s_256 = Hash(0xb260)
+	HashBlake2b_256 = Hash(0xb220)
+	HashBlake2b_384 = Hash(0xb230)
+	HashBlake2b_512 = Hash(0xb240)
+
+	HashShake_256 = Hash(0x19)
+
+	HashKeccak256 = Hash(0x1b)
+	HashKeccak512 = Hash(0x1d)
 )

 // DecodeHashAlgorithm reads and validates the expected hash algorithm
 // (for varsig types include a variable hash algorithm.)
-func DecodeHashAlgorithm(r *bytes.Reader) (HashAlgorithm, error) {
+func DecodeHashAlgorithm(r BytesReader) (Hash, error) {
 	u, err := binary.ReadUvarint(r)
 	if err != nil {
-		return HashAlgorithmUnspecified, fmt.Errorf("%w: %w", ErrUnknownHashAlgorithm, err)
+		return HashUnspecified, fmt.Errorf("%w: %w", ErrUnknownHash, err)
 	}

-	h := HashAlgorithm(u)
+	h := Hash(u)

 	switch h {
-	case HashAlgorithmSHA256,
-		HashAlgorithmSHA384,
-		HashAlgorithmSHA512,
-		HashAlgorithmShake256:
+	case HashSha2_224,
+		HashSha2_256,
+		HashSha2_384,
+		HashSha2_512,
+		HashSha3_224,
+		HashSha3_256,
+		HashSha3_384,
+		HashSha3_512,
+		HashSha512_224,
+		HashSha512_256,
+		HashBlake2s_256,
+		HashBlake2b_256,
+		HashBlake2b_384,
+		HashBlake2b_512,
+		HashShake_256,
+		HashKeccak256,
+		HashKeccak512:
 		return h, nil
 	default:
-		return HashAlgorithmUnspecified, fmt.Errorf("%w: %x", ErrUnknownHashAlgorithm, h)
+		return HashUnspecified, fmt.Errorf("%w: %x", ErrUnknownHash, h)
 	}
 }

 // PayloadEncoding specifies the encoding of the data being (hashed and)
 // signed.  A canonical representation of the data is required to produce
 // consistent hashes and signatures.
-type PayloadEncoding uint64
+type PayloadEncoding int

-// Constant multicodec.Code values that allow Varsig implementations to
-// specify how the payload content is encoded before being hashed.  In
-// varsig >= v1, only canonical encoding is allowed.
+// Constant values that allow Varsig implementations to specify how the
+// payload content is encoded before being hashed.
+// In varsig >= v1, only canonical encoding is allowed.
 const (
-	PayloadEncodingUnspecified PayloadEncoding = 0x00
-	PayloadEncodingVerbatim    PayloadEncoding = 0x5f
-	PayloadEncodingDAGPB                       = PayloadEncoding(multicodec.DagPb)
-	PayloadEncodingDAGCBOR                     = PayloadEncoding(multicodec.DagCbor)
-	PayloadEncodingDAGJSON                     = PayloadEncoding(multicodec.DagJson)
-	PayloadEncodingEIP191                      = PayloadEncoding(multicodec.Eip191)
-	PayloadEncodingJWT         PayloadEncoding = 0x6a77
+	PayloadEncodingUnspecified = PayloadEncoding(iota)
+	PayloadEncodingVerbatim
+	PayloadEncodingDAGPB
+	PayloadEncodingDAGCBOR
+	PayloadEncodingDAGJSON
+	PayloadEncodingEIP191Raw
+	PayloadEncodingEIP191Cbor
+	PayloadEncodingJWT
+)
+
+const (
+	encodingSegmentVerbatim = uint64(0x5f)
+	encodingSegmentDAGPB    = uint64(0x70)
+	encodingSegmentDAGCBOR  = uint64(0x71)
+	encodingSegmentDAGJSON  = uint64(0x0129)
+	encodingSegmentEIP191   = uint64(0xe191)
+	encodingSegmentJWT      = uint64(0x6a77)
 )

 // DecodePayloadEncoding reads and validates the expected canonical payload
 // encoding of the data to be signed.
-func DecodePayloadEncoding(r *bytes.Reader, vers Version) (PayloadEncoding, error) {
-	u, err := binary.ReadUvarint(r)
+func DecodePayloadEncoding(r BytesReader, vers Version) (PayloadEncoding, error) {
+	seg1, err := binary.ReadUvarint(r)
 	if err != nil {
 		return PayloadEncodingUnspecified, fmt.Errorf("%w: %w", ErrUnsupportedPayloadEncoding, err)
 	}

-	payEnc := PayloadEncoding(u)
-
 	switch vers {
 	case Version0:
-		return decodeEncodingInfoV0(payEnc)
+		switch seg1 {
+		case encodingSegmentVerbatim:
+			return PayloadEncodingVerbatim, nil
+		case encodingSegmentDAGPB:
+			return PayloadEncodingDAGPB, nil
+		case encodingSegmentDAGCBOR:
+			return PayloadEncodingDAGCBOR, nil
+		case encodingSegmentDAGJSON:
+			return PayloadEncodingDAGJSON, nil
+		case encodingSegmentEIP191:
+			seg2, err := binary.ReadUvarint(r)
+			if err != nil {
+				return PayloadEncodingUnspecified, fmt.Errorf("%w: incomplete EIP191 encoding: %w", ErrUnsupportedPayloadEncoding, err)
+			}
+			switch seg2 {
+			case encodingSegmentVerbatim:
+				return PayloadEncodingEIP191Raw, nil
+			case encodingSegmentDAGCBOR:
+				return PayloadEncodingEIP191Cbor, nil
+			default:
+				return PayloadEncodingUnspecified, fmt.Errorf("%w: version=%d, encoding=%x+%x", ErrUnsupportedPayloadEncoding, vers, seg1, seg2)
+			}
+		case encodingSegmentJWT:
+			return PayloadEncodingJWT, nil
+		default:
+			return PayloadEncodingUnspecified, fmt.Errorf("%w: version=%d, encoding=%x", ErrUnsupportedPayloadEncoding, vers, seg1)
+		}
 	case Version1:
-		return decodeEncodingInfoV1(payEnc)
+		switch seg1 {
+		case encodingSegmentVerbatim:
+			return PayloadEncodingVerbatim, nil
+		case encodingSegmentDAGCBOR:
+			return PayloadEncodingDAGCBOR, nil
+		case encodingSegmentDAGJSON:
+			return PayloadEncodingDAGJSON, nil
+		case encodingSegmentEIP191:
+			seg2, err := binary.ReadUvarint(r)
+			if err != nil {
+				return PayloadEncodingUnspecified, fmt.Errorf("%w: incomplete EIP191 encoding: %w", ErrUnsupportedPayloadEncoding, err)
+			}
+			switch seg2 {
+			case encodingSegmentVerbatim:
+				return PayloadEncodingEIP191Raw, nil
+			case encodingSegmentDAGCBOR:
+				return PayloadEncodingEIP191Cbor, nil
+			default:
+				return PayloadEncodingUnspecified, fmt.Errorf("%w: version=%d, encoding=%x+%x", ErrUnsupportedPayloadEncoding, vers, seg1, seg2)
+			}
+		default:
+			return PayloadEncodingUnspecified, fmt.Errorf("%w: version=%d, encoding=%x", ErrUnsupportedPayloadEncoding, vers, seg1)
+		}
 	default:
 		return 0, ErrUnsupportedVersion
 	}
 }

-// https://github.com/ChainAgnostic/varsig#4-payload-encoding
-func decodeEncodingInfoV0(payEnc PayloadEncoding) (PayloadEncoding, error) {
-	switch payEnc {
-	case PayloadEncodingVerbatim,
-		PayloadEncodingDAGPB,
-		PayloadEncodingDAGCBOR,
-		PayloadEncodingDAGJSON,
-		PayloadEncodingJWT,
-		PayloadEncodingEIP191:
-		return payEnc, nil
+// EncodePayloadEncoding returns the PayloadEncoding as serialized bytes.
+// If enc is not a valid PayloadEncoding, this function will panic.
+func EncodePayloadEncoding(enc PayloadEncoding) []byte {
+	res := make([]byte, 0, 8)
+	switch enc {
+	case PayloadEncodingVerbatim:
+		res = binary.AppendUvarint(res, encodingSegmentVerbatim)
+	case PayloadEncodingDAGPB:
+		res = binary.AppendUvarint(res, encodingSegmentDAGPB)
+	case PayloadEncodingDAGCBOR:
+		res = binary.AppendUvarint(res, encodingSegmentDAGCBOR)
+	case PayloadEncodingDAGJSON:
+		res = binary.AppendUvarint(res, encodingSegmentDAGJSON)
+	case PayloadEncodingEIP191Raw:
+		res = binary.AppendUvarint(res, encodingSegmentEIP191)
+		res = binary.AppendUvarint(res, encodingSegmentVerbatim)
+	case PayloadEncodingEIP191Cbor:
+		res = binary.AppendUvarint(res, encodingSegmentEIP191)
+		res = binary.AppendUvarint(res, encodingSegmentDAGCBOR)
+	case PayloadEncodingJWT:
+		res = binary.AppendUvarint(res, encodingSegmentJWT)
 	default:
-		return PayloadEncodingUnspecified, fmt.Errorf("%w: version=%d, encoding=%x", ErrUnsupportedPayloadEncoding, Version0, payEnc)
+		panic(fmt.Sprintf("invalid encoding: %v", enc))
 	}
+
+	return res
 }

-// https://github.com/expede/varsig/blob/main/README.md#payload-encoding
-func decodeEncodingInfoV1(payEnc PayloadEncoding) (PayloadEncoding, error) {
-	switch payEnc {
-	case PayloadEncodingVerbatim,
-		PayloadEncodingDAGCBOR,
-		PayloadEncodingDAGJSON,
-		PayloadEncodingEIP191:
-		return payEnc, nil
-	default:
-		return PayloadEncodingUnspecified, fmt.Errorf("%w: version=%d, encoding=%x", ErrUnsupportedPayloadEncoding, Version1, payEnc)
-	}
-}
-
-// Discriminator is (usually) the multicodec.Code representing the public
-// key type of the algorithm used to create the signature.
+// Discriminator is (usually) the value representing the public key type of
+// the algorithm used to create the signature.
 //
-// There is not set list of constants here, nor is there a decode function
+// There is no set list of constants here, nor is there a decode function
 // as the author of an implementation should include the constant with the
 // implementation, and the decoding is handled by the Handler, which uses
 // the Discriminator to choose the correct implementation.  Also note that
--- a/constant_test.go
+++ b/constant_test.go
@@ -18,24 +18,24 @@ func TestDecodeHashAlgorithm(t *testing.T) {

 		hashAlg, err := varsig.DecodeHashAlgorithm(bytes.NewReader([]byte{0x12}))
 		require.NoError(t, err)
-		require.Equal(t, varsig.HashAlgorithmSHA256, hashAlg)
+		require.Equal(t, varsig.HashSha2_256, hashAlg)
 	})

 	t.Run("fails - truncated varsig (no bytes)", func(t *testing.T) {
 		t.Parallel()

 		hashAlg, err := varsig.DecodeHashAlgorithm(bytes.NewReader([]byte{}))
-		require.ErrorIs(t, err, varsig.ErrUnknownHashAlgorithm)
+		require.ErrorIs(t, err, varsig.ErrUnknownHash)
 		require.ErrorIs(t, err, io.EOF)
-		require.Equal(t, varsig.HashAlgorithmUnspecified, hashAlg)
+		require.Equal(t, varsig.HashUnspecified, hashAlg)
 	})

 	t.Run("fails - unknown hash algorithm", func(t *testing.T) {
 		t.Parallel()

 		hashAlg, err := varsig.DecodeHashAlgorithm(bytes.NewReader([]byte{0x42}))
-		require.ErrorIs(t, err, varsig.ErrUnknownHashAlgorithm)
-		require.Equal(t, varsig.HashAlgorithmUnspecified, hashAlg)
+		require.ErrorIs(t, err, varsig.ErrUnknownHash)
+		require.Equal(t, varsig.HashUnspecified, hashAlg)
 	})
 }

--- a/ecdsa.go
+++ b/ecdsa.go
@@ -1,9 +1,155 @@
 package varsig

-// Stub
-const (
-	DiscriminatorECDSASecp256k1 Discriminator = 0xe7
-	DiscriminatorECDSAP256      Discriminator = 0x1200
-	DiscriminatorECDSAP384      Discriminator = 0x1201
-	DiscriminatorECDSAP521      Discriminator = 0x1202
+import (
+	"encoding/binary"
+	"fmt"
 )
+
+// DiscriminatorECDSA is the value specifying an ECDSA signature.
+const DiscriminatorECDSA = Discriminator(0xec)
+
+// ECDSACurve are values that specify which ECDSA curve is used when
+// generating the signature.
+type ECDSACurve uint64
+
+// Constants describing the values for each specific ECDSA curve that can
+// be encoded into a Varsig.
+const (
+	CurveSecp256k1 = ECDSACurve(0xe7)
+	CurveP256      = ECDSACurve(0x1200)
+	CurveP384      = ECDSACurve(0x1201)
+	CurveP521      = ECDSACurve(0x1202)
+)
+
+func decodeECDSACurve(r BytesReader) (ECDSACurve, error) {
+	u, err := binary.ReadUvarint(r)
+	if err != nil {
+		return 0, err
+	}
+
+	switch curve := ECDSACurve(u); curve {
+	case CurveSecp256k1, CurveP256, CurveP384, CurveP521:
+		return curve, nil
+	default:
+		return 0, fmt.Errorf("%w: %x", ErrUnknownECDSACurve, u)
+	}
+}
+
+var _ Varsig = ECDSAVarsig{}
+
+// ECDSAVarsig is a varsig that encodes the parameters required to describe
+// an ECDSA signature.
+type ECDSAVarsig struct {
+	varsig
+
+	curve   ECDSACurve
+	hashAlg Hash
+}
+
+// NewECDSAVarsig creates and validates an ECDSA varsig with the provided
+// curve, hash algorithm and payload encoding.
+func NewECDSAVarsig(curve ECDSACurve, hashAlgorithm Hash, payloadEncoding PayloadEncoding, opts ...Option) (ECDSAVarsig, error) {
+	options := newOptions(opts...)
+
+	var (
+		vers = Version1
+		disc = DiscriminatorECDSA
+		sig  []byte
+	)
+
+	if options.ForceVersion0() {
+		vers = Version0
+		disc = Discriminator(curve)
+		sig = options.Signature()
+	}
+
+	v := ECDSAVarsig{
+		varsig: varsig{
+			vers:   vers,
+			disc:   disc,
+			payEnc: payloadEncoding,
+			sig:    sig,
+		},
+		curve:   curve,
+		hashAlg: hashAlgorithm,
+	}
+
+	switch curve {
+	case CurveSecp256k1, CurveP256:
+		return validateSig(v, 64)
+	case CurveP384:
+		return validateSig(v, 96)
+	case CurveP521:
+		return validateSig(v, 132)
+	default:
+		return ECDSAVarsig{}, fmt.Errorf("%w: %x", ErrUnknownECDSACurve, curve)
+	}
+}
+
+// Curve returns the elliptic curve used to generate the ECDSA signature.
+func (v ECDSAVarsig) Curve() ECDSACurve {
+	return v.curve
+}
+
+// Hash returns the value describing the hash algorithm used to hash
+// the payload content before the signature is generated.
+func (v ECDSAVarsig) Hash() Hash {
+	return v.hashAlg
+}
+
+// Encode returns the encoded byte format of the ECDSAVarsig.
+func (v ECDSAVarsig) Encode() []byte {
+	buf := v.encode()
+
+	if v.vers != Version0 {
+		buf = binary.AppendUvarint(buf, uint64(v.curve))
+	}
+
+	buf = binary.AppendUvarint(buf, uint64(v.hashAlg))
+	buf = append(buf, EncodePayloadEncoding(v.payEnc)...)
+	buf = append(buf, v.Signature()...)
+
+	return buf
+}
+
+func decodeECDSA(r BytesReader, vers Version, disc Discriminator) (Varsig, error) {
+	curve := ECDSACurve(disc)
+	if vers != Version0 {
+		var err error
+
+		curve, err = decodeECDSACurve(r)
+		if err != nil {
+			return nil, err
+		}
+	}
+
+	hashAlg, err := DecodeHashAlgorithm(r)
+	if err != nil {
+		return nil, err
+	}
+
+	v := ECDSAVarsig{
+		varsig: varsig{
+			vers: vers,
+			disc: disc,
+		},
+		curve:   curve,
+		hashAlg: hashAlg,
+	}
+
+	v.payEnc, v.sig, err = v.decodePayEncAndSig(r)
+	if err != nil {
+		return nil, err
+	}
+
+	switch curve {
+	case CurveSecp256k1, CurveP256:
+		return validateSig(v, 64)
+	case CurveP384:
+		return validateSig(v, 96)
+	case CurveP521:
+		return validateSig(v, 132)
+	default:
+		return ECDSAVarsig{}, fmt.Errorf("%w: %x", ErrUnknownECDSACurve, curve)
+	}
+}
--- a/eddsa.go
+++ b/eddsa.go
@@ -1,51 +1,59 @@
 package varsig

 import (
-	"bytes"
 	"crypto/ed25519"
 	"encoding/binary"
-
-	"github.com/multiformats/go-multicodec"
+	"fmt"
 )

-// Constants containing multicodec.Code values that specify EdDSA signatures.
-const (
-	DiscriminatorEdDSA   = Discriminator(multicodec.Ed25519Pub)
-	DiscriminatorEd25519 = Discriminator(multicodec.Ed25519Pub)
-	DiscriminatorEd448   = Discriminator(multicodec.Ed448Pub)
-)
+// DiscriminatorEdDSA is the value specifying an EdDSA signature.
+const DiscriminatorEdDSA = Discriminator(0xed)

-// EdDSACurve are multicodec.Code values that specify which Edwards curve
-// is used when generating the signature.
+// EdDSACurve are values that specify which Edwards curve is used when
+// generating the signature.
 type EdDSACurve uint64

-// Constants describing the multicodec.Code for each specific Edwards
-// curve that can be encoded into a Varsig.
+// Constants describing the values for each specific Edwards curve that can
+// be encoded into a Varsig.
 const (
-	CurveEd25519 = EdDSACurve(multicodec.Ed25519Pub)
-	CurveEd448   = EdDSACurve(multicodec.Ed448Pub)
+	CurveEd25519 = EdDSACurve(0xed)
+	CurveEd448   = EdDSACurve(0x1203)
 )

-var _ Varsig = (*EdDSAVarsig)(nil)
+func decodeEdDSACurve(r BytesReader) (EdDSACurve, error) {
+	u, err := binary.ReadUvarint(r)
+	if err != nil {
+		return 0, err
+	}
+
+	switch curve := EdDSACurve(u); curve {
+	case CurveEd25519, CurveEd448:
+		return curve, nil
+	default:
+		return 0, fmt.Errorf("%w: %x", ErrUnknownEdDSACurve, u)
+	}
+}
+
+var _ Varsig = EdDSAVarsig{}

 // EdDSAVarsig is a varsig that encodes the parameters required to describe
 // an EdDSA signature.
 type EdDSAVarsig struct {
-	varsig[EdDSAVarsig]
+	varsig

 	curve   EdDSACurve
-	hashAlg HashAlgorithm
+	hashAlg Hash
 }

 // NewEdDSAVarsig creates and validates an EdDSA varsig with the provided
 // curve, hash algorithm and payload encoding.
-func NewEdDSAVarsig(curve EdDSACurve, hashAlgorithm HashAlgorithm, payloadEncoding PayloadEncoding, opts ...Option) (*EdDSAVarsig, error) {
+func NewEdDSAVarsig(curve EdDSACurve, hashAlgorithm Hash, payloadEncoding PayloadEncoding, opts ...Option) (EdDSAVarsig, error) {
 	options := newOptions(opts...)

 	var (
 		vers = Version1
 		disc = DiscriminatorEdDSA
-		sig  = []byte{}
+		sig  []byte
 	)

 	if options.ForceVersion0() {
@@ -54,8 +62,8 @@ func NewEdDSAVarsig(curve EdDSACurve, hashAlgorithm HashAlgorithm, payloadEncodi
 		sig = options.Signature()
 	}

-	v := &EdDSAVarsig{
-		varsig: varsig[EdDSAVarsig]{
+	v := EdDSAVarsig{
+		varsig: varsig{
 			vers:   vers,
 			disc:   disc,
 			payEnc: payloadEncoding,
@@ -65,17 +73,24 @@ func NewEdDSAVarsig(curve EdDSACurve, hashAlgorithm HashAlgorithm, payloadEncodi
 		hashAlg: hashAlgorithm,
 	}

-	return v.validateSig(v, ed25519.PrivateKeySize)
+	switch curve {
+	case CurveEd25519:
+		return validateSig(v, ed25519.SignatureSize)
+	case CurveEd448:
+		return validateSig(v, 114)
+	default:
+		return EdDSAVarsig{}, fmt.Errorf("%w: %x", ErrUnknownEdDSACurve, curve)
+	}
 }

 // Curve returns the Edwards curve used to generate the EdDSA signature.
-func (v *EdDSAVarsig) Curve() EdDSACurve {
+func (v EdDSAVarsig) Curve() EdDSACurve {
 	return v.curve
 }

-// HashAlgorithm returns the multicodec.Code describing the hash algorithm
-// used to hash the payload content before the signature is generated.
-func (v *EdDSAVarsig) HashAlgorithm() HashAlgorithm {
+// Hash returns the value describing the hash algorithm used to hash
+// the payload content before the signature is generated.
+func (v EdDSAVarsig) Hash() Hash {
 	return v.hashAlg
 }

@@ -88,37 +103,48 @@ func (v EdDSAVarsig) Encode() []byte {
 	}

 	buf = binary.AppendUvarint(buf, uint64(v.hashAlg))
-	buf = binary.AppendUvarint(buf, uint64(v.payEnc))
+	buf = append(buf, EncodePayloadEncoding(v.payEnc)...)
 	buf = append(buf, v.Signature()...)

 	return buf
 }

-func decodeEd25519(r *bytes.Reader, vers Version, disc Discriminator) (Varsig, error) {
-	curve := uint64(disc)
+func decodeEdDSA(r BytesReader, vers Version, disc Discriminator) (Varsig, error) {
+	curve := EdDSACurve(disc)
 	if vers != Version0 {
-		u, err := binary.ReadUvarint(r)
+		var err error

+		curve, err = decodeEdDSACurve(r)
 		if err != nil {
-			return nil, err // TODO: wrap error?
+			return nil, err
 		}
-
-		curve = u
 	}

-	hashAlg, err := binary.ReadUvarint(r)
+	hashAlg, err := DecodeHashAlgorithm(r)
 	if err != nil {
-		return nil, err // TODO: wrap error?
+		return nil, err
 	}

-	v := &EdDSAVarsig{
-		varsig: varsig[EdDSAVarsig]{
+	v := EdDSAVarsig{
+		varsig: varsig{
 			vers: vers,
 			disc: disc,
 		},
-		curve:   EdDSACurve(curve),
-		hashAlg: HashAlgorithm(hashAlg),
+		curve:   curve,
+		hashAlg: hashAlg,
 	}

-	return v.decodePayEncAndSig(r, v, ed25519.PrivateKeySize)
+	v.payEnc, v.sig, err = v.decodePayEncAndSig(r)
+	if err != nil {
+		return nil, err
+	}
+
+	switch curve {
+	case CurveEd25519:
+		return validateSig(v, ed25519.SignatureSize)
+	case CurveEd448:
+		return validateSig(v, 114)
+	default:
+		return EdDSAVarsig{}, fmt.Errorf("%w: %x", ErrUnknownEdDSACurve, curve)
+	}
 }
--- a/eddsa_test.go
+++ b/eddsa_test.go
@@ -1,6 +1,7 @@
 package varsig_test

 import (
+	"encoding/base64"
 	"encoding/hex"
 	"testing"

@@ -31,14 +32,14 @@ func TestDecodeEd25519(t *testing.T) {
 			require.NoError(t, err)
 			require.NotNil(t, v)
 			assert.Equal(t, varsig.Version0, v.Version())
-			assert.Equal(t, varsig.DiscriminatorEd25519, v.Discriminator())
+			assert.Equal(t, varsig.DiscriminatorEdDSA, v.Discriminator())
 			assert.Equal(t, varsig.PayloadEncodingDAGCBOR, v.PayloadEncoding())
 			assert.Len(t, v.Signature(), 64)

-			impl, ok := v.(*varsig.EdDSAVarsig)
+			impl, ok := v.(varsig.EdDSAVarsig)
 			require.True(t, ok)
 			assert.Equal(t, varsig.CurveEd25519, impl.Curve())
-			assert.Equal(t, varsig.HashAlgorithmSHA512, impl.HashAlgorithm())
+			assert.Equal(t, varsig.HashSha2_512, impl.Hash())
 		})

 		t.Run("Encode", func(t *testing.T) {
@@ -46,7 +47,7 @@ func TestDecodeEd25519(t *testing.T) {

 			v, err := varsig.NewEdDSAVarsig(
 				varsig.CurveEd25519,
-				varsig.HashAlgorithmSHA512,
+				varsig.HashSha2_512,
 				varsig.PayloadEncodingDAGCBOR,
 				varsig.WithForceVersion0(sig),
 			)
@@ -56,3 +57,44 @@ func TestDecodeEd25519(t *testing.T) {
 		})
 	})
 }
+
+func TestUCANExampleV1(t *testing.T) {
+	t.Parallel()
+
+	// This test is the value shown in the UCAN v1.0.0 example, which is
+	// an EdDSA varsig = v1 with the Ed25519 curve, SHA2_256 hashing and
+	// DAG-CBOR content encoding.
+	example, err := base64.RawStdEncoding.DecodeString("NAHtAe0BE3E")
+	require.NoError(t, err)
+
+	t.Run("Decode", func(t *testing.T) {
+		t.Parallel()
+
+		v, err := varsig.Decode(example)
+		require.NoError(t, err)
+
+		ed25519V, ok := v.(varsig.EdDSAVarsig)
+		require.True(t, ok)
+
+		assert.Equal(t, varsig.Version1, ed25519V.Version())
+		assert.Equal(t, varsig.DiscriminatorEdDSA, ed25519V.Discriminator())
+		assert.Equal(t, varsig.CurveEd25519, ed25519V.Curve())
+		assert.Equal(t, varsig.HashSha2_512, ed25519V.Hash())
+		assert.Equal(t, varsig.PayloadEncodingDAGCBOR, ed25519V.PayloadEncoding())
+		assert.Len(t, ed25519V.Signature(), 0)
+	})
+
+	t.Run("Encode", func(t *testing.T) {
+		t.Parallel()
+
+		edDSAVarsig, err := varsig.NewEdDSAVarsig(
+			varsig.CurveEd25519,
+			varsig.HashSha2_512,
+			varsig.PayloadEncodingDAGCBOR,
+		)
+		require.NoError(t, err)
+
+		assert.Equal(t, example, edDSAVarsig.Encode())
+		t.Log(base64.RawStdEncoding.EncodeToString(edDSAVarsig.Encode()))
+	})
+}
--- a/error.go
+++ b/error.go
@@ -13,7 +13,7 @@ var ErrMissingSignature = errors.New("missing signature expected in varsig v0")
 var ErrNotYetImplemented = errors.New("not yet implemented")

 // ErrUnexpectedSignaturePresent is returned when a signature is present
-// in  a varsig >= v1.
+// in a varsig >= v1.
 var ErrUnexpectedSignaturePresent = errors.New("unexpected signature present in varsig >= v1")

 // ErrUnexpectedSignatureSize is returned when the length of the decoded
@@ -21,23 +21,31 @@ var ErrUnexpectedSignaturePresent = errors.New("unexpected signature present in
 // signing algorithm or sent via a Varsig field.
 var ErrUnexpectedSignatureSize = errors.New("unexpected signature size in varsig v0")

-// ErrUnknownHashAlgoritm is returned when an unexpected value is provided
+// ErrUnknownHash is returned when an unexpected value is provided
 // while decoding the hashing algorithm.
-var ErrUnknownHashAlgorithm = errors.New("unknown hash algorithm")
+var ErrUnknownHash = errors.New("unknown hash algorithm")

 // ErrUnsupportedPayloadEncoding is returned when an unexpected value is
 // provided while decoding the payload encoding field.  The allowed values
 // for this field may vary based on the varsig version.
 var ErrUnsupportedPayloadEncoding = errors.New("unsupported payload encoding")

-// ErrUnknowndiscorith is returned when the Registry doesn't have a
+// ErrUnknownDiscriminator is returned when the Registry doesn't have a
 // parsing function for the decoded signing algorithm.
 var ErrUnknownDiscriminator = errors.New("unknown signing algorithm")

+// ErrUnknownEdDSACurve is returned when the decoded uvarint isn't either
+// CurveEd25519 or CurveEd448.
+var ErrUnknownEdDSACurve = errors.New("unknown Edwards curve")
+
+// ErrUnknownECDSACurve is returned when the decoded uvarint isn't either
+// CurveSecp256k1, CurveP256, CurveP384 or CurveP521.
+var ErrUnknownECDSACurve = errors.New("unknown ECDSA curve")
+
 // ErrUnsupportedVersion is returned when an unsupported varsig version
 // field is present.
 var ErrUnsupportedVersion = errors.New("unsupported version")

 // ErrBadPrefix is returned when the prefix field contains a value other
-// than 0x34 (encoded as a uvarint).
+// than 0x34 (encoded as an uvarint).
 var ErrBadPrefix = errors.New("varsig prefix not found")
--- a/go.mod
+++ b/go.mod
@@ -1,11 +1,10 @@
 module github.com/ucan-wg/go-varsig

-go 1.24.4
+go 1.23.10

-require (
-	github.com/multiformats/go-multicodec v0.9.2
-	github.com/stretchr/testify v1.10.0
-)
+toolchain go1.24.4
+
+require github.com/stretchr/testify v1.10.0

 require (
 	github.com/davecgh/go-spew v1.1.1 // indirect
--- a/go.sum
+++ b/go.sum
@@ -6,8 +6,6 @@ github.com/google/go-cmp v0.6.0 h1:ofyhxvXcZhMsU5ulbFiLKl/XBFqE1GSq7atu8tAmTRI=
 github.com/google/go-cmp v0.6.0/go.mod h1:17dUlkBOakJ0+DkrSSNjCkIjxS6bF9zb3elmeNGIjoY=
 github.com/google/renameio v0.1.0 h1:GOZbcHa3HfsPKPlmyPyN2KEohoMXOhdMbHrvbpl2QaA=
 github.com/google/renameio v0.1.0/go.mod h1:KWCgfxg9yswjAJkECMjeO8J8rahYeXnNhOm40UhjYkI=
-github.com/multiformats/go-multicodec v0.9.2 h1:YrlXCuqxjqm3bXl+vBq5LKz5pz4mvAsugdqy78k0pXQ=
-github.com/multiformats/go-multicodec v0.9.2/go.mod h1:LLWNMtyV5ithSBUo3vFIMaeDy+h3EbkMTek1m+Fybbo=
 github.com/pmezard/go-difflib v1.0.0 h1:4DBwDE0NGyQoBHbLQYPwSUPoCMWR5BEzIk/f1lZbAQM=
 github.com/pmezard/go-difflib v1.0.0/go.mod h1:iKH77koFhYxTK1pcRnkKkqfTogsbg7gZNVY4sRDYZ/4=
 github.com/stretchr/testify v1.10.0 h1:Xv5erBjTwe/5IxqUQTdXv5kgmIvbHo3QQyRwhJsOfJA=
--- a/registry.go
+++ b/registry.go
@@ -6,11 +6,11 @@ import (
 	"fmt"
 )

-// Version represents which version of the vasig specification was used
+// Version represents which version of the varsig specification was used
 // to produce Varsig value.
 type Version uint64

-// Constancts for the existing varsig specifications
+// Constants for the existing varsig specifications
 const (
 	Version0 Version = 0
 	Version1 Version = 1
@@ -18,9 +18,9 @@ const (

 // DecodeFunc is a function that parses the varsig representing a specific
 // signing algorithm.
-type DecodeFunc func(*bytes.Reader, Version, Discriminator) (Varsig, error)
+type DecodeFunc func(BytesReader, Version, Discriminator) (Varsig, error)

-// Registry contains a mapping between known signing algorithms, and
+// Registry contains a mapping between known signing algorithms and
 // functions that can parse varsigs for that signing algorithm.
 type Registry map[Discriminator]DecodeFunc

@@ -28,12 +28,9 @@ type Registry map[Discriminator]DecodeFunc
 // signing algorithms which have an implementation within this library.
 func DefaultRegistry() Registry {
 	return map[Discriminator]DecodeFunc{
-		DiscriminatorRSA:            decodeRSA,
-		DiscriminatorEdDSA:          decodeEd25519,
-		DiscriminatorEd448:          decodeEd25519,
-		DiscriminatorECDSAP256:      notYetImplementedVarsigDecoder,
-		DiscriminatorECDSASecp256k1: notYetImplementedVarsigDecoder,
-		DiscriminatorECDSAP521:      notYetImplementedVarsigDecoder,
+		DiscriminatorRSA:   decodeRSA,
+		DiscriminatorEdDSA: decodeEdDSA,
+		DiscriminatorECDSA: decodeECDSA,
 	}
 }

@@ -56,7 +53,7 @@ func (rs Registry) Decode(data []byte) (Varsig, error) {

 // DecodeStream converts data read from the provided io.Reader into one
 // of the registered Varsig types.
-func (rs Registry) DecodeStream(r *bytes.Reader) (Varsig, error) {
+func (rs Registry) DecodeStream(r BytesReader) (Varsig, error) {
 	pre, err := binary.ReadUvarint(r)
 	if err != nil {
 		return nil, fmt.Errorf("%w: %w", ErrBadPrefix, err)
@@ -79,7 +76,7 @@ func (rs Registry) DecodeStream(r *bytes.Reader) (Varsig, error) {
 	return decodeFunc(r, vers, disc)
 }

-func (rs Registry) decodeVersAnddisc(r *bytes.Reader) (Version, Discriminator, error) {
+func (rs Registry) decodeVersAnddisc(r BytesReader) (Version, Discriminator, error) {
 	vers, err := binary.ReadUvarint(r)
 	if err != nil {
 		return Version(vers), 0, err
@@ -97,7 +94,3 @@ func (rs Registry) decodeVersAnddisc(r *bytes.Reader) (Version, Discriminator, e

 	return Version(vers), Discriminator(disc), err
 }
-
-func notYetImplementedVarsigDecoder(_ *bytes.Reader, vers Version, disc Discriminator) (Varsig, error) {
-	return nil, fmt.Errorf("%w: Version: %d, Discriminator: %x", ErrNotYetImplemented, vers, disc)
-}
--- a/registry_test.go
+++ b/registry_test.go
@@ -61,7 +61,7 @@ func testRegistry(t *testing.T) varsig.Registry {
 func testDecodeFunc(t *testing.T) varsig.DecodeFunc {
 	t.Helper()

-	return func(r *bytes.Reader, vers varsig.Version, disc varsig.Discriminator) (varsig.Varsig, error) {
+	return func(r varsig.BytesReader, vers varsig.Version, disc varsig.Discriminator) (varsig.Varsig, error) {
 		v := &testVarsig{
 			vers: vers,
 			disc: disc,
@@ -71,7 +71,7 @@ func testDecodeFunc(t *testing.T) varsig.DecodeFunc {
 	}
 }

-var _ varsig.Varsig = (*testVarsig)(nil)
+var _ varsig.Varsig = testVarsig{}

 type testVarsig struct {
 	vers   varsig.Version
@@ -80,22 +80,22 @@ type testVarsig struct {
 	sig    []byte
 }

-func (v *testVarsig) Version() varsig.Version {
+func (v testVarsig) Version() varsig.Version {
 	return v.vers
 }

-func (v *testVarsig) Discriminator() varsig.Discriminator {
+func (v testVarsig) Discriminator() varsig.Discriminator {
 	return v.disc
 }

-func (v *testVarsig) PayloadEncoding() varsig.PayloadEncoding {
+func (v testVarsig) PayloadEncoding() varsig.PayloadEncoding {
 	return v.payEnc
 }

-func (v *testVarsig) Signature() []byte {
+func (v testVarsig) Signature() []byte {
 	return v.sig
 }

-func (v *testVarsig) Encode() []byte {
+func (v testVarsig) Encode() []byte {
 	return nil
 }
--- a/rsa.go
+++ b/rsa.go
@@ -1,33 +1,30 @@
 package varsig

 import (
-	"bytes"
 	"encoding/binary"
-
-	"github.com/multiformats/go-multicodec"
 )

-// DiscriminatorRSA is the multicodec.Code specifying an RSA signature.
-const DiscriminatorRSA = Discriminator(multicodec.RsaPub)
+// DiscriminatorRSA is the value specifying an RSA signature.
+const DiscriminatorRSA = Discriminator(0x1205)

-var _ Varsig = (*RSAVarsig)(nil)
+var _ Varsig = RSAVarsig{}

 // RSAVarsig is a varsig that encodes the parameters required to describe
 // an RSA signature.
 type RSAVarsig struct {
-	varsig[RSAVarsig]
-	hashAlg HashAlgorithm
+	varsig
+	hashAlg Hash
 	sigLen  uint64
 }

 // NewRSAVarsig creates and validates an RSA varsig with the provided
 // hash algorithm, key length and payload encoding.
-func NewRSAVarsig(hashAlgorithm HashAlgorithm, keyLength uint64, payloadEncoding PayloadEncoding, opts ...Option) (*RSAVarsig, error) {
+func NewRSAVarsig(hashAlgorithm Hash, keyLength uint64, payloadEncoding PayloadEncoding, opts ...Option) (RSAVarsig, error) {
 	options := newOptions(opts...)

 	var (
 		vers = Version1
-		sig  = []byte{}
+		sig  []byte
 	)

 	if options.ForceVersion0() {
@@ -35,8 +32,8 @@ func NewRSAVarsig(hashAlgorithm HashAlgorithm, keyLength uint64, payloadEncoding
 		sig = options.Signature()
 	}

-	v := &RSAVarsig{
-		varsig: varsig[RSAVarsig]{
+	v := RSAVarsig{
+		varsig: varsig{
 			vers:   vers,
 			disc:   DiscriminatorRSA,
 			payEnc: payloadEncoding,
@@ -46,7 +43,7 @@ func NewRSAVarsig(hashAlgorithm HashAlgorithm, keyLength uint64, payloadEncoding
 		sigLen:  keyLength,
 	}

-	return v.validateSig(v, v.sigLen)
+	return validateSig(v, v.sigLen)
 }

 // Encode returns the encoded byte format of the RSAVarsig.
@@ -54,24 +51,25 @@ func (v RSAVarsig) Encode() []byte {
 	buf := v.encode()
 	buf = binary.AppendUvarint(buf, uint64(v.hashAlg))
 	buf = binary.AppendUvarint(buf, v.sigLen)
-	buf = binary.AppendUvarint(buf, uint64(v.payEnc))
+	buf = append(buf, EncodePayloadEncoding(v.payEnc)...)
 	buf = append(buf, v.Signature()...)

 	return buf
 }

-// HashAlgorithm returns the hash algorithm used to has the payload content.
-func (v *RSAVarsig) HashAlgorithm() HashAlgorithm {
+// Hash returns the value describing the hash algorithm used to hash
+// the payload content before the signature is generated.
+func (v RSAVarsig) Hash() Hash {
 	return v.hashAlg
 }

 // KeyLength returns the length of the RSA key used to sign the payload
 // content.
-func (v *RSAVarsig) KeyLength() uint64 {
+func (v RSAVarsig) KeyLength() uint64 {
 	return v.sigLen
 }

-func decodeRSA(r *bytes.Reader, vers Version, disc Discriminator) (Varsig, error) {
+func decodeRSA(r BytesReader, vers Version, disc Discriminator) (Varsig, error) {
 	hashAlg, err := DecodeHashAlgorithm(r)
 	if err != nil {
 		return nil, err
@@ -82,14 +80,19 @@ func decodeRSA(r *bytes.Reader, vers Version, disc Discriminator) (Varsig, error
 		return nil, err
 	}

-	vs := &RSAVarsig{
-		varsig: varsig[RSAVarsig]{
+	vs := RSAVarsig{
+		varsig: varsig{
 			vers: vers,
 			disc: disc,
 		},
-		hashAlg: HashAlgorithm(hashAlg),
+		hashAlg: hashAlg,
 		sigLen:  sigLen,
 	}

-	return vs.decodePayEncAndSig(r, vs, sigLen)
+	vs.payEnc, vs.sig, err = vs.decodePayEncAndSig(r)
+	if err != nil {
+		return nil, err
+	}
+
+	return validateSig(vs, vs.sigLen)
 }
--- a/rsa_test.go
+++ b/rsa_test.go
@@ -26,12 +26,12 @@ func TestRSAVarsig(t *testing.T) {
 		vs, err := varsig.Decode(example)
 		require.NoError(t, err)

-		rsaVs, ok := vs.(*varsig.RSAVarsig)
+		rsaVs, ok := vs.(varsig.RSAVarsig)
 		require.True(t, ok)

 		assert.Equal(t, varsig.Version1, rsaVs.Version())
 		assert.Equal(t, varsig.DiscriminatorRSA, rsaVs.Discriminator())
-		assert.Equal(t, varsig.HashAlgorithmSHA256, rsaVs.HashAlgorithm())
+		assert.Equal(t, varsig.HashSha2_256, rsaVs.Hash())
 		assert.Equal(t, varsig.PayloadEncodingDAGCBOR, rsaVs.PayloadEncoding())
 		assert.Equal(t, uint64(keyLen), rsaVs.KeyLength())
 		assert.Len(t, rsaVs.Signature(), 0)
@@ -41,7 +41,7 @@ func TestRSAVarsig(t *testing.T) {
 		t.Parallel()

 		rsaVarsig, err := varsig.NewRSAVarsig(
-			varsig.HashAlgorithmSHA256,
+			varsig.HashSha2_256,
 			keyLen,
 			varsig.PayloadEncodingDAGCBOR,
 		)
@@ -52,7 +52,7 @@ func TestRSAVarsig(t *testing.T) {
 	})
 }

-func TestUCANExample(t *testing.T) {
+func TestUCANExampleV0(t *testing.T) {
 	t.Parallel()

 	const keyLen = 0x100
@@ -69,12 +69,12 @@ func TestUCANExample(t *testing.T) {
 		vs, err := varsig.Decode(example)
 		require.ErrorIs(t, err, varsig.ErrMissingSignature)

-		rsaVs, ok := vs.(*varsig.RSAVarsig)
+		rsaVs, ok := vs.(varsig.RSAVarsig)
 		require.True(t, ok)

 		assert.Equal(t, varsig.Version0, rsaVs.Version())
 		assert.Equal(t, varsig.DiscriminatorRSA, rsaVs.Discriminator())
-		assert.Equal(t, varsig.HashAlgorithmSHA256, rsaVs.HashAlgorithm())
+		assert.Equal(t, varsig.HashSha2_256, rsaVs.Hash())
 		assert.Equal(t, varsig.PayloadEncodingDAGCBOR, rsaVs.PayloadEncoding())
 		assert.Equal(t, uint64(keyLen), rsaVs.KeyLength())
 		assert.Len(t, rsaVs.Signature(), 0)
@@ -84,7 +84,7 @@ func TestUCANExample(t *testing.T) {
 		t.Parallel()

 		rsaVarsig, err := varsig.NewRSAVarsig(
-			varsig.HashAlgorithmSHA256,
+			varsig.HashSha2_256,
 			keyLen,
 			varsig.PayloadEncodingDAGCBOR,
 			varsig.WithForceVersion0([]byte{}),
--- a/varsig.go
+++ b/varsig.go
@@ -19,21 +19,29 @@
 package varsig

 import (
-	"bytes"
 	"encoding/binary"
+	"errors"
 	"io"
 )

 // Varsig represents types that describe how a signature was generated
 // and thus how to interpret the signature and verify the signed data.
 type Varsig interface {
-	// accessors for fields that are common to all varsig
+	// Version returns the varsig's version field.
 	Version() Version
+
+	// Discriminator returns the algorithm used to produce the corresponding signature.
 	Discriminator() Discriminator
+
+	// PayloadEncoding returns the codec that was used to encode the signed data.
 	PayloadEncoding() PayloadEncoding
+
+	// Signature returns the cryptographic signature of the signed data.
+	// This value is never present in a varsig >= v1 and must either be a valid
+	// signature with the correct length or empty in varsig < v1.
 	Signature() []byte

-	// Operations that are common to all varsig
+	// Encode returns the encoded byte format of the varsig.
 	Encode() []byte
 }

@@ -45,11 +53,11 @@ func Decode(data []byte) (Varsig, error) {

 // DecodeStream converts data read from the provided io.Reader into one
 // of the Varsig types provided by the DefaultRegistry.
-func DecodeStream(r *bytes.Reader) (Varsig, error) {
+func DecodeStream(r BytesReader) (Varsig, error) {
 	return DefaultRegistry().DecodeStream(r)
 }

-type varsig[T Varsig] struct {
+type varsig struct {
 	vers   Version
 	disc   Discriminator
 	payEnc PayloadEncoding
@@ -57,31 +65,34 @@ type varsig[T Varsig] struct {
 }

 // Version returns the varsig's version field.
-func (v varsig[_]) Version() Version {
+func (v varsig) Version() Version {
 	return v.vers
 }

-// Discriminator returns the algorithm used to produce corresponding
+// Discriminator returns the algorithm used to produce the corresponding
 // signature.
-func (v varsig[_]) Discriminator() Discriminator {
+func (v varsig) Discriminator() Discriminator {
 	return v.disc
 }

 // PayloadEncoding returns the codec that was used to encode the signed
 // data.
-func (v varsig[_]) PayloadEncoding() PayloadEncoding {
+func (v varsig) PayloadEncoding() PayloadEncoding {
 	return v.payEnc
 }

 // Signature returns the cryptographic signature of the signed data. This
 // value is never present in a varsig >= v1 and must either be a valid
 // signature with the correct length or empty in varsig < v1.
-func (v varsig[_]) Signature() []byte {
+func (v varsig) Signature() []byte {
 	return v.sig
 }

-func (v *varsig[_]) encode() []byte {
-	var buf []byte
+func (v varsig) encode() []byte {
+	// Pre-allocate to the maximum size to avoid re-allocating.
+	// I think the maximum is 10 bytes, but it's all the same for go to allocate 16 (due to the small
+	// size allocation class), so we might as well get some headroom for bigger varints.
+	buf := make([]byte, 0, 16)

 	buf = binary.AppendUvarint(buf, Prefix)

@@ -94,37 +105,51 @@ func (v *varsig[_]) encode() []byte {
 	return buf
 }

-func (v *varsig[T]) decodePayEncAndSig(r *bytes.Reader, varsig *T, expectedLength uint64) (*T, error) {
+func (v varsig) decodePayEncAndSig(r BytesReader) (PayloadEncoding, []byte, error) {
 	payEnc, err := DecodePayloadEncoding(r, v.Version())
 	if err != nil {
-		return nil, err
+		return 0, nil, err
 	}

-	v.payEnc = payEnc
-
-	signature, err := io.ReadAll(r)
-	if err != nil {
-		return nil, err
+	var signature []byte
+	switch v.Version() {
+	case Version0:
+		signature, err = io.ReadAll(r)
+		if err != nil {
+			return 0, nil, err
+		}
+	case Version1:
+		_, err := r.ReadByte()
+		if err != nil && !errors.Is(err, io.EOF) {
+			return 0, nil, err
+		}
+		if err == nil {
+			return 0, nil, ErrUnexpectedSignaturePresent
+		}
+	default:
+		return 0, nil, ErrUnsupportedVersion
 	}

-	v.sig = signature
-
-	return v.validateSig(varsig, expectedLength)
+	return payEnc, signature, nil
 }

-func (v *varsig[T]) validateSig(varsig *T, expectedLength uint64) (*T, error) {
-	if v.Version() == Version0 && len(v.sig) == 0 {
-		return varsig, ErrMissingSignature
+func validateSig[T Varsig](v T, expectedLength uint64) (T, error) {
+	if v.Version() == Version0 && len(v.Signature()) == 0 {
+		return v, ErrMissingSignature
 	}

-	if v.Version() == Version0 && uint64(len(v.sig)) != expectedLength {
-		return nil, ErrUnexpectedSignatureSize
+	if v.Version() == Version0 && uint64(len(v.Signature())) != expectedLength {
+		return *new(T), ErrUnexpectedSignatureSize
 	}

-	if v.Version() == Version1 && len(v.sig) != 0 {
-		return nil, ErrUnexpectedSignaturePresent
+	if v.Version() == Version1 && len(v.Signature()) != 0 {
+		return *new(T), ErrUnexpectedSignaturePresent
 	}

-	return varsig, nil
-
+	return v, nil
+}
+
+type BytesReader interface {
+	io.ByteReader
+	io.Reader
 }
--- a/varsig_test.go
+++ b/varsig_test.go
@@ -2,7 +2,6 @@ package varsig_test

 import (
 	"encoding/hex"
-	"errors"
 	"io"
 	"testing"

@@ -133,7 +132,7 @@ func TestDecode(t *testing.T) {

 		vs, err := varsig.Decode(data)
 		require.ErrorIs(t, err, varsig.ErrUnexpectedSignatureSize)
-		assert.Nil(t, vs)
+		assert.Zero(t, vs)
 	})

 	t.Run("fails - unexpected signature present - v1", func(t *testing.T) {
@@ -157,32 +156,3 @@ func TestDecode(t *testing.T) {
 		assert.NotNil(t, vs) // varsig is still returned with just "header"
 	})
 }
-
-func mustVarsig[T varsig.Varsig](t *testing.T) func(*T, error) *T {
-	t.Helper()
-
-	return func(v *T, err error) *T {
-		if err != nil && ((*v).Version() != varsig.Version0 || !errors.Is(err, varsig.ErrMissingSignature)) {
-			t.Error(err)
-		}
-
-		return v
-	}
-}
-
-func roundTrip[T varsig.Varsig](t *testing.T, in T, expEncHex string) T {
-	data := in.Encode()
-	assert.Equal(t, expEncHex, hex.EncodeToString(data))
-
-	out, err := varsig.Decode(in.Encode())
-	if err != nil && (out.Version() != varsig.Version0 || !errors.Is(err, varsig.ErrMissingSignature)) {
-		t.Fail()
-	}
-
-	assert.Equal(t, in.Version(), out.Version())
-	assert.Equal(t, in.Discriminator(), out.Discriminator())
-	assert.Equal(t, in.PayloadEncoding(), out.PayloadEncoding())
-	assert.Equal(t, in.Signature(), out.Signature())
-
-	return out.(T)
-}
Author	SHA1	Message	Date
Michael Muré	35ef54f79f	feat: turns out, PayloadEncoding can be multiple values for EIP191	2025-07-24 16:52:58 +02:00
Michael Muré	2f22cb9b15	feat(test): add more tests for the presets, and compat with iso-ucan	2025-07-24 16:52:58 +02:00
Michael Muré	a43c3af4c8	feat(ecdsa): implement varsig for EdDSA	2025-07-22 14:24:39 +02:00
Michael Muré	eab24207bc	fix(eddsa): ed25519 or ed448 should be curves, not discriminator	2025-07-22 13:57:22 +02:00
Michael Muré	be01529d44	perf: pre-allocate the buffer when encoding a varsig	2025-07-22 13:10:12 +02:00
Michael Muré	182036b055	fix(eddsa): fix the size of the signature check for ed448	2025-07-22 12:04:31 +02:00
Michael Muré	0763d6f8b6	feat(hashes): shorten HashAlgorithm to Hash, add more of them	2025-07-22 12:03:56 +02:00
Michael Muré	c7a870e9db	readme: add authorship and license	2025-07-11 07:28:42 +02:00
Steve Moyer	2238f3a26c	build: run GitHub checks only once	2025-07-10 10:47:33 -04:00
Steve Moyer	f2cd448a11	build: support Go v1.23.10 downstream	2025-07-10 10:10:35 -04:00
Steve Moyer	25d4579b29	test(ucan): add test for updated UCAN example varsig	2025-07-10 06:46:07 -04:00
Michael Muré	5fb3516d15	feat(deps): remove the multicodec dependency, as varsig constants are not multicodec	2025-07-10 12:39:27 +02:00
Michael Muré	eb70826a70	varsig: handle unknown version with an error	2025-07-09 13:39:09 +02:00
Michael Muré	6308c66ab7	update varsig documentation	2025-07-09 13:39:09 +02:00
Steve Moyer	f6b72f1907	fix(v0): restores validateSig behavior	2025-07-09 13:39:09 +02:00
Michael Muré	03770e0d38	use value receiver, remove unneeded generic	2025-07-09 13:39:09 +02:00
Steve Moyer	1ea8b00efd	Merge pull request #1 from ucan-wg/constants-alloc perf(constants): avoid allocating a map for each Decode*() call	2025-07-08 11:53:19 -04:00
Steve Moyer	21a78a9d2d	fix(eddsa): use DecodeHashAlgorithm and create decodeEdDSACurve	2025-07-08 11:27:18 -04:00