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

.github/workflows/pre-commit.yaml

@@ -1,9 +1,7 @@
 name: pre-commit
 
 on:
-  pull_request:
   push:
-    # branches: [main]
 
 jobs:
   pre-commit:

.pre-commit-config.yaml

@@ -31,7 +31,7 @@ repos:
     - id: my-cmd-repo
       alias: govulncheck
       name: govulncheck
-      args: ["bash", "-c", "go run golang.org/x/vuln/cmd/govulncheck@v1.1.4 ./..."]
+      args: ["bash", "-c", "go tool golang.org/x/vuln/cmd/govulncheck ./..."]
 - repo: https://github.com/alessandrojcm/commitlint-pre-commit-hook
   rev: v9.22.0
   hooks:

.tool-versions

@@ -1,4 +1,4 @@
 act 0.2.79
 golang 1.24.4
 golangci-lint 2.2.1
-pre-commit 4.2.0
+pre-commit 4.0.1

README.md

@@ -5,6 +5,8 @@ with limited (and soon to be deprecated) support for the `varsig` < 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:
@@ -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)

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
+
+// 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, HashAlgorithmSHA512, payloadEncoding, opts...)
+	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
+// 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, HashAlgorithmShake256, payloadEncoding, opts...)
+	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
+// 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(HashAlgorithmSHA256, keyLength, payloadEncoding, opts...)
+	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
+// 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(HashAlgorithmSHA384, keyLength, payloadEncoding, opts...)
+	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
+// 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(HashAlgorithmSHA512, keyLength, payloadEncoding, opts...)
+	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...)
 }

common_test.go

@@ -1,68 +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, err := varsig.Ed25519(varsig.PayloadEncodingDAGCBOR)
-	mustVarsig(t, in, err)
-	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, err := varsig.Ed448(varsig.PayloadEncodingDAGCBOR)
-	mustVarsig(t, in, err)
-	out := roundTrip(t, in, "3401ed0183241971")
-	assertEdDSAEqual(t, in, out)
-}
-
-func TestRS256(t *testing.T) {
-	t.Parallel()
-
-	in, err := varsig.RS256(0x100, varsig.PayloadEncodingDAGCBOR)
-	mustVarsig(t, in, err)
-	out := roundTrip(t, in, "3401852412800271")
-	assertRSAEqual(t, in, out)
-}
-
-func TestRS384(t *testing.T) {
-	t.Parallel()
-
-	in, err := varsig.RS384(0x100, varsig.PayloadEncodingDAGCBOR)
-	mustVarsig(t, in, err)
-	out := roundTrip(t, in, "3401852420800271")
-	assertRSAEqual(t, in, out)
-}
-
-func TestRS512(t *testing.T) {
-	t.Parallel()
-
-	in, err := varsig.RS512(0x100, varsig.PayloadEncodingDAGCBOR)
-	mustVarsig(t, in, err)
-	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
 }

constant.go

@@ -8,111 +8,199 @@ import (
 // Prefix is the value for the varsig's varuint prefix byte.
 const Prefix = uint64(0x34)
 
-// HashAlgorithm is the value 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 values that allow Varsig implementations to specify how
 // the payload content is hashed before the signature is generated.
 const (
-	HashAlgorithmUnspecified HashAlgorithm = 0x00
-	HashAlgorithmSHA256                    = HashAlgorithm(0x12)
-	HashAlgorithmSHA384                    = HashAlgorithm(0x20)
-	HashAlgorithmSHA512                    = HashAlgorithm(0x13)
-	HashAlgorithmShake256                  = HashAlgorithm(0x19)
+	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 BytesReader) (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 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(0x70)
-	PayloadEncodingDAGCBOR                     = PayloadEncoding(0x71)
-	PayloadEncodingDAGJSON                     = PayloadEncoding(0x0129)
-	PayloadEncodingEIP191                      = PayloadEncoding(0xd191)
-	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 BytesReader, vers Version) (PayloadEncoding, error) {
-	u, err := binary.ReadUvarint(r)
+	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))
 	}
-}
 
-// 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)
-	}
+	return res
 }
 
 // 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

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)
 	})
 }
 

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)
+	}
+}

eddsa.go

@@ -6,12 +6,8 @@ import (
 	"fmt"
 )
 
-// Constants containing values that specify EdDSA signatures.
-const (
-	DiscriminatorEdDSA   = Discriminator(0xed)
-	DiscriminatorEd25519 = Discriminator(0xed)
-	DiscriminatorEd448   = Discriminator(0x1203)
-)
+// DiscriminatorEdDSA is the value specifying an EdDSA signature.
+const DiscriminatorEdDSA = Discriminator(0xed)
 
 // EdDSACurve are values that specify which Edwards curve is used when
 // generating the signature.
@@ -46,12 +42,12 @@ type EdDSAVarsig struct {
 	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 (
@@ -77,7 +73,14 @@ func NewEdDSAVarsig(curve EdDSACurve, hashAlgorithm HashAlgorithm, payloadEncodi
 		hashAlg: hashAlgorithm,
 	}
 
-	return validateSig(v, ed25519.SignatureSize)
+	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.
@@ -85,9 +88,9 @@ func (v EdDSAVarsig) Curve() EdDSACurve {
 	return v.curve
 }
 
-// HashAlgorithm returns the value describing the hash algorithm used to hash
+// Hash returns the value describing the hash algorithm used to hash
 // the payload content before the signature is generated.
-func (v EdDSAVarsig) HashAlgorithm() HashAlgorithm {
+func (v EdDSAVarsig) Hash() Hash {
 	return v.hashAlg
 }
 
@@ -100,13 +103,13 @@ 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 BytesReader, vers Version, disc Discriminator) (Varsig, error) {
+func decodeEdDSA(r BytesReader, vers Version, disc Discriminator) (Varsig, error) {
 	curve := EdDSACurve(disc)
 	if vers != Version0 {
 		var err error
@@ -136,5 +139,12 @@ func decodeEd25519(r BytesReader, vers Version, disc Discriminator) (Varsig, err
 		return nil, err
 	}
 
-	return validateSig(v, ed25519.SignatureSize)
+	switch curve {
+	case CurveEd25519:
+		return validateSig(v, ed25519.SignatureSize)
+	case CurveEd448:
+		return validateSig(v, 114)
+	default:
+		return EdDSAVarsig{}, fmt.Errorf("%w: %x", ErrUnknownEdDSACurve, curve)
+	}
 }

eddsa_test.go

@@ -32,14 +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)
 			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) {
@@ -47,7 +47,7 @@ func TestDecodeEd25519(t *testing.T) {
 
 			v, err := varsig.NewEdDSAVarsig(
 				varsig.CurveEd25519,
-				varsig.HashAlgorithmSHA512,
+				varsig.HashSha2_512,
 				varsig.PayloadEncodingDAGCBOR,
 				varsig.WithForceVersion0(sig),
 			)
@@ -73,15 +73,15 @@ func TestUCANExampleV1(t *testing.T) {
 		v, err := varsig.Decode(example)
 		require.NoError(t, err)
 
-		rsaV, ok := v.(varsig.EdDSAVarsig)
+		ed25519V, ok := v.(varsig.EdDSAVarsig)
 		require.True(t, ok)
 
-		assert.Equal(t, varsig.Version1, rsaV.Version())
-		assert.Equal(t, varsig.DiscriminatorEdDSA, rsaV.Discriminator())
-		assert.Equal(t, varsig.CurveEd25519, rsaV.Curve())
-		assert.Equal(t, varsig.HashAlgorithmSHA512, rsaV.HashAlgorithm())
-		assert.Equal(t, varsig.PayloadEncodingDAGCBOR, rsaV.PayloadEncoding())
-		assert.Len(t, rsaV.Signature(), 0)
+		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) {
@@ -89,7 +89,7 @@ func TestUCANExampleV1(t *testing.T) {
 
 		edDSAVarsig, err := varsig.NewEdDSAVarsig(
 			varsig.CurveEd25519,
-			varsig.HashAlgorithmSHA512,
+			varsig.HashSha2_512,
 			varsig.PayloadEncodingDAGCBOR,
 		)
 		require.NoError(t, err)

error.go

@@ -21,9 +21,9 @@ 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")
 
-// ErrUnknownHashAlgorithm 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
@@ -38,6 +38,10 @@ var ErrUnknownDiscriminator = errors.New("unknown signing algorithm")
 // 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")

go.mod

@@ -1,11 +1,21 @@
 module github.com/ucan-wg/go-varsig
 
-go 1.24.4
+go 1.23.10
+
+toolchain go1.24.4
 
 require github.com/stretchr/testify v1.10.0
 
 require (
 	github.com/davecgh/go-spew v1.1.1 // indirect
 	github.com/pmezard/go-difflib v1.0.0 // indirect
+	golang.org/x/mod v0.22.0 // indirect
+	golang.org/x/sync v0.10.0 // indirect
+	golang.org/x/sys v0.29.0 // indirect
+	golang.org/x/telemetry v0.0.0-20240522233618-39ace7a40ae7 // indirect
+	golang.org/x/tools v0.29.0 // indirect
+	golang.org/x/vuln v1.1.4 // indirect
 	gopkg.in/yaml.v3 v3.0.1 // indirect
 )
+
+tool golang.org/x/vuln/cmd/govulncheck

go.sum

@@ -1,9 +1,27 @@
 github.com/davecgh/go-spew v1.1.1 h1:vj9j/u1bqnvCEfJOwUhtlOARqs3+rkHYY13jYWTU97c=
 github.com/davecgh/go-spew v1.1.1/go.mod h1:J7Y8YcW2NihsgmVo/mv3lAwl/skON4iLHjSsI+c5H38=
+github.com/google/go-cmdtest v0.4.1-0.20220921163831-55ab3332a786 h1:rcv+Ippz6RAtvaGgKxc+8FQIpxHgsF+HBzPyYL2cyVU=
+github.com/google/go-cmdtest v0.4.1-0.20220921163831-55ab3332a786/go.mod h1:apVn/GCasLZUVpAJ6oWAuyP7Ne7CEsQbTnc0plM3m+o=
+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/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=
 github.com/stretchr/testify v1.10.0/go.mod h1:r2ic/lqez/lEtzL7wO/rwa5dbSLXVDPFyf8C91i36aY=
+golang.org/x/mod v0.22.0 h1:D4nJWe9zXqHOmWqj4VMOJhvzj7bEZg4wEYa759z1pH4=
+golang.org/x/mod v0.22.0/go.mod h1:6SkKJ3Xj0I0BrPOZoBy3bdMptDDU9oJrpohJ3eWZ1fY=
+golang.org/x/sync v0.10.0 h1:3NQrjDixjgGwUOCaF8w2+VYHv0Ve/vGYSbdkTa98gmQ=
+golang.org/x/sync v0.10.0/go.mod h1:Czt+wKu1gCyEFDUtn0jG5QVvpJ6rzVqr5aXyt9drQfk=
+golang.org/x/sys v0.29.0 h1:TPYlXGxvx1MGTn2GiZDhnjPA9wZzZeGKHHmKhHYvgaU=
+golang.org/x/sys v0.29.0/go.mod h1:/VUhepiaJMQUp4+oa/7Zr1D23ma6VTLIYjOOTFZPUcA=
+golang.org/x/telemetry v0.0.0-20240522233618-39ace7a40ae7 h1:FemxDzfMUcK2f3YY4H+05K9CDzbSVr2+q/JKN45pey0=
+golang.org/x/telemetry v0.0.0-20240522233618-39ace7a40ae7/go.mod h1:pRgIJT+bRLFKnoM1ldnzKoxTIn14Yxz928LQRYYgIN0=
+golang.org/x/tools v0.29.0 h1:Xx0h3TtM9rzQpQuR4dKLrdglAmCEN5Oi+P74JdhdzXE=
+golang.org/x/tools v0.29.0/go.mod h1:KMQVMRsVxU6nHCFXrBPhDB8XncLNLM0lIy/F14RP588=
+golang.org/x/vuln v1.1.4 h1:Ju8QsuyhX3Hk8ma3CesTbO8vfJD9EvUBgHvkxHBzj0I=
+golang.org/x/vuln v1.1.4/go.mod h1:F+45wmU18ym/ca5PLTPLsSzr2KppzswxPP603ldA67s=
 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/yaml.v3 v3.0.1 h1:fxVm/GzAzEWqLHuvctI91KS9hhNmmWOoWu0XTYJS7CA=

registry.go

@@ -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,
 	}
 }
 
@@ -97,7 +94,3 @@ func (rs Registry) decodeVersAnddisc(r BytesReader) (Version, Discriminator, err
 
 	return Version(vers), Discriminator(disc), err
 }
-
-func notYetImplementedVarsigDecoder(_ BytesReader, vers Version, disc Discriminator) (Varsig, error) {
-	return nil, fmt.Errorf("%w: Version: %d, Discriminator: %x", ErrNotYetImplemented, vers, disc)
-}

rsa.go

@@ -13,13 +13,13 @@ var _ Varsig = RSAVarsig{}
 // an RSA signature.
 type RSAVarsig struct {
 	varsig
-	hashAlg HashAlgorithm
+	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 (
@@ -51,14 +51,15 @@ 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
 }
 

rsa_test.go

@@ -31,7 +31,7 @@ func TestRSAVarsig(t *testing.T) {
 
 		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,
 		)
@@ -74,7 +74,7 @@ func TestUCANExampleV0(t *testing.T) {
 
 		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 TestUCANExampleV0(t *testing.T) {
 		t.Parallel()
 
 		rsaVarsig, err := varsig.NewRSAVarsig(
-			varsig.HashAlgorithmSHA256,
+			varsig.HashSha2_256,
 			keyLen,
 			varsig.PayloadEncodingDAGCBOR,
 			varsig.WithForceVersion0([]byte{}),

varsig.go

@@ -89,7 +89,10 @@ func (v varsig) Signature() []byte {
 }
 
 func (v varsig) encode() []byte {
-	var buf []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)
 

varsig_test.go

@@ -2,7 +2,6 @@ package varsig_test
 
 import (
 	"encoding/hex"
-	"errors"
 	"io"
 	"testing"
 
@@ -157,28 +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, v T, err error) {
-	t.Helper()
-
-	if err != nil && (v.Version() != varsig.Version0 || !errors.Is(err, varsig.ErrMissingSignature)) {
-		t.Error(err)
-	}
-}
-
-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)
-}