psbt: add new fields for MuSig2

btcec/schnorr/musig2/sign.go

@@ -195,9 +195,9 @@ func WithBip86SignTweak() SignOption {
 	}
 }
 
-// computeSigningNonce calculates the final nonce used for signing. This will
+// ComputeSigningNonce calculates the final nonce used for signing. This will
 // be the R value used in the final signature.
-func computeSigningNonce(combinedNonce [PubNonceSize]byte,
+func ComputeSigningNonce(combinedNonce [PubNonceSize]byte,
 	combinedKey *btcec.PublicKey, msg [32]byte) (
 	*btcec.JacobianPoint, *btcec.ModNScalar, error) {
 
@@ -313,7 +313,7 @@ func Sign(secNonce [SecNonceSize]byte, privKey *btcec.PrivateKey,
 	// We'll now combine both the public nonces, using the blinding factor
 	// to tweak the second nonce:
 	//  * R = R_1 + b*R_2
-	nonce, nonceBlinder, err := computeSigningNonce(
+	nonce, nonceBlinder, err := ComputeSigningNonce(
 		combinedNonce, combinedKey.FinalKey, msg,
 	)
 	if err != nil {

btcec/schnorr/musig2/sign_test.go

@@ -391,7 +391,7 @@ func TestMusig2SignCombine(t *testing.T) {
 			combinedNonce, err := AggregateNonces(pubNonces)
 			require.NoError(t, err)
 
-			finalNonceJ, _, err := computeSigningNonce(
+			finalNonceJ, _, err := ComputeSigningNonce(
 				combinedNonce, combinedKey.FinalKey, msg,
 			)
 

btcec/schnorr/signature.go

@@ -15,8 +15,8 @@ const (
 	// SignatureSize is the size of an encoded Schnorr signature.
 	SignatureSize = 64
 
-	// scalarSize is the size of an encoded big endian scalar.
-	scalarSize = 32
+	// ScalarSize is the size of an encoded big endian scalar.
+	ScalarSize = 32
 )
 
 var (
@@ -132,9 +132,9 @@ func schnorrVerify(sig *Signature, hash []byte, pubKeyBytes []byte) error {
 	// Step 1.
 	//
 	// Fail if m is not 32 bytes
-	if len(hash) != scalarSize {
+	if len(hash) != ScalarSize {
 		str := fmt.Sprintf("wrong size for message (got %v, want %v)",
-			len(hash), scalarSize)
+			len(hash), ScalarSize)
 		return signatureError(ecdsa_schnorr.ErrInvalidHashLen, str)
 	}
 
@@ -234,8 +234,8 @@ func (sig *Signature) Verify(hash []byte, pubKey *btcec.PublicKey) bool {
 }
 
 // zeroArray zeroes the memory of a scalar array.
-func zeroArray(a *[scalarSize]byte) {
-	for i := 0; i < scalarSize; i++ {
+func zeroArray(a *[ScalarSize]byte) {
+	for i := 0; i < ScalarSize; i++ {
 		a[i] = 0x00
 	}
 }
@@ -444,9 +444,9 @@ func Sign(privKey *btcec.PrivateKey, hash []byte,
 	// Step 2.
 	//
 	// Fail if m is not 32 bytes
-	if len(hash) != scalarSize {
+	if len(hash) != ScalarSize {
 		str := fmt.Sprintf("wrong size for message hash (got %v, want %v)",
-			len(hash), scalarSize)
+			len(hash), ScalarSize)
 		return nil, signatureError(ecdsa_schnorr.ErrInvalidHashLen, str)
 	}
 
@@ -519,7 +519,7 @@ func Sign(privKey *btcec.PrivateKey, hash []byte,
 		return sig, nil
 	}
 
-	var privKeyBytes [scalarSize]byte
+	var privKeyBytes [ScalarSize]byte
 	privKeyScalar.PutBytes(&privKeyBytes)
 	defer zeroArray(&privKeyBytes)
 	for iteration := uint32(0); ; iteration++ {