Add 1.3.6 changelog, test IEEE P1363 sigs in DSSE (#2063)

* Bump sigstore/sigstore, add 1.3.6 changelog

Signed-off-by: Hayden Blauzvern <hblauzvern@google.com>

* Add test

Signed-off-by: Hayden Blauzvern <hblauzvern@google.com>

---------

Signed-off-by: Hayden Blauzvern <hblauzvern@google.com>

CHANGELOG.md

@@ -1,3 +1,26 @@
+# v1.3.6
+
+## New Features
+
+* Add support for IEEE P1363 encoded ECDSA signatures
+* Add index performance script (#2042)
+* Add support for ed25519ph user keys in hashedrekord (#1945)
+* Add metrics for index insertion (#2015)
+* Add TLS support for Redis Client implementation (#1998)
+
+## Bug Fixes
+
+* fix typo in remoteIp and set full name for trace field
+
+## Contributors
+
+* Bob Callaway
+* Colleen Murphy
+* cpanato
+* Hayden B
+* Mihkel Pärna
+* Riccardo Schirone
+
 # v1.3.5
 
 ## New Features

pkg/types/dsse/v0.0.1/entry_test.go

@@ -24,6 +24,7 @@ import (
 	"crypto/rand"
 	"crypto/sha256"
 	"crypto/x509"
+	"encoding/asn1"
 	"encoding/base64"
 	"encoding/hex"
 	"encoding/json"
@@ -62,6 +63,52 @@ func TestNewEntryReturnType(t *testing.T) {
 	}
 }
 
+type ecdsaSignature struct {
+	R, S *big.Int
+}
+
+// From https://github.com/tink-crypto/tink/blob/43c17d490a6c8391bb5384278963cb59f4b65495/go/signature/subtle/encoding.go#L62
+func ieeeSignatureSize(curveName string) (int, error) {
+	switch curveName {
+	case elliptic.P256().Params().Name:
+		return 64, nil
+	case elliptic.P384().Params().Name:
+		return 96, nil
+	case elliptic.P521().Params().Name:
+		return 132, nil
+	default:
+		return 0, fmt.Errorf("ieeeP1363 unsupported curve name: %q", curveName)
+	}
+}
+
+// From https://github.com/tink-crypto/tink/blob/43c17d490a6c8391bb5384278963cb59f4b65495/go/signature/subtle/encoding.go#L75
+func ieeeP1363Encode(sig *ecdsaSignature, curveName string) ([]byte, error) {
+	sigSize, err := ieeeSignatureSize(curveName)
+	if err != nil {
+		return nil, err
+	}
+
+	enc := make([]byte, sigSize)
+
+	// sigR and sigS must be half the size of the signature. If not, we need to pad them with zeros.
+	offset := 0
+	if len(sig.R.Bytes()) < (sigSize / 2) {
+		offset += (sigSize / 2) - len(sig.R.Bytes())
+	}
+	// Copy sigR after any zero-padding.
+	copy(enc[offset:], sig.R.Bytes())
+
+	// Skip the bytes of sigR.
+	offset = sigSize / 2
+	if len(sig.S.Bytes()) < (sigSize / 2) {
+		offset += (sigSize / 2) - len(sig.S.Bytes())
+	}
+	// Copy sigS after sigR and any zero-padding.
+	copy(enc[offset:], sig.S.Bytes())
+
+	return enc, nil
+}
+
 func envelope(t *testing.T, k *ecdsa.PrivateKey, payload []byte) *dsse.Envelope {
 
 	s, err := signature.LoadECDSASigner(k, crypto.SHA256)
@@ -118,6 +165,30 @@ func createRekorEnvelope(dsseEnv *dsse.Envelope, pub [][]byte) *models.DSSEV001S
 	return proposedContent
 }
 
+// transformECDSASignatures converts ASN.1 encoded ECDSA signatures (SEQ{r, s})
+// to IEEE P1363 encoding (r||s)
+func transformECDSASignatures(t *testing.T, k *ecdsa.PrivateKey, dsseEnv *dsse.Envelope) *dsse.Envelope {
+	sigs := dsseEnv.Signatures
+	var newSigs []dsse.Signature
+	for _, b64sig := range sigs {
+		sig, err := base64.StdEncoding.DecodeString(b64sig.Sig)
+		if err != nil {
+			t.Fatal(err)
+		}
+		ecdsaSig := ecdsaSignature{}
+		if _, err := asn1.Unmarshal(sig, &ecdsaSig); err != nil {
+			t.Fatal(err)
+		}
+		ieeeP1363Sig, err := ieeeP1363Encode(&ecdsaSig, k.Params().Name)
+		if err != nil {
+			t.Fatal(err)
+		}
+		newSigs = append(newSigs, dsse.Signature{KeyID: b64sig.KeyID, Sig: base64.StdEncoding.EncodeToString(ieeeP1363Sig)})
+	}
+	dsseEnv.Signatures = newSigs
+	return dsseEnv
+}
+
 func TestV001Entry_Unmarshal(t *testing.T) {
 	key, err := ecdsa.GenerateKey(elliptic.P256(), rand.Reader)
 	if err != nil {
@@ -197,6 +268,22 @@ func TestV001Entry_Unmarshal(t *testing.T) {
 			},
 			wantErr: false,
 		},
+		{
+			env:  envelope(t, key, []byte(validPayload)),
+			name: "key with IEEE P1361 sig",
+			it: &models.DSSEV001Schema{
+				ProposedContent: createRekorEnvelope(transformECDSASignatures(t, key, envelope(t, key, []byte(validPayload))), [][]byte{pub}),
+			},
+			wantErr: false,
+		},
+		{
+			env:  envelope(t, priv, []byte(validPayload)),
+			name: "cert with IEEE P1361 sig",
+			it: &models.DSSEV001Schema{
+				ProposedContent: createRekorEnvelope(transformECDSASignatures(t, priv, envelope(t, priv, []byte(validPayload))), [][]byte{pemBytes}),
+			},
+			wantErr: false,
+		},
 		{
 			env:  &invalid,
 			name: "invalid",