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WIP support for low-R grinding #234

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16 changes: 12 additions & 4 deletions secp-ffm/src/main/java/org/bitcoinj/secp/ffm/Secp256k1Foreign.java
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Original file line number Diff line number Diff line change
Expand Up @@ -259,7 +259,7 @@ public byte[] ecPubKeySerialize(SecpPubKey pubKey, int flags) {
// public SecpPoint.Uncompressed ecPointUncompress(SecpPoint.Compressed compressedPoint) {
// return compressedPoint.uncompress();
// }

/* package */ static MemorySegment pubKeySerializeSegment(MemorySegment pubKeySegment, int flags) {
int byteSize = switch(flags) {
case 2 -> 65; // SECP256K1_EC_UNCOMPRESSED())
Expand Down Expand Up @@ -303,16 +303,24 @@ private MemorySegment pubKeyParse(SecpPubKey pubKeyData) {

@Override
public SecpResult<EcdsaSignature> ecdsaSign(byte[] msg_hash_data, SecpPrivKey seckey) {
return ecdsaSign(msg_hash_data, seckey, secp256k1_h.NULL());
}

public SecpResult<EcdsaSignature> ecdsaSign(byte[] msg_hash_data, SecpPrivKey seckey, byte[] ndata) {
// TODO: validate ndata is exactly 32-bytes long
return ecdsaSign(msg_hash_data, seckey, arena.allocateFrom(JAVA_BYTE, ndata));
}

public SecpResult<EcdsaSignature> ecdsaSign(byte[] msg_hash_data, SecpPrivKey seckey, MemorySegment ndataSegment) {
/* Generate an ECDSA signature `noncefp` and `ndata` allows you to pass a
* custom nonce function, passing `NULL` will use the RFC-6979 safe default.
* Signing with a valid context, verified secret key
* and the default nonce function should never fail. */
MemorySegment msg_hash = arena.allocateFrom(JAVA_BYTE, msg_hash_data);
MemorySegment sig = secp256k1_ecdsa_signature.allocate(arena);
MemorySegment nullCallback = secp256k1_h.NULL(); // Double-check this (normally you shouldn't use a NULL pointer for a null callback)
MemorySegment nullPointer = secp256k1_h.NULL();
MemorySegment nonceFpNull = secp256k1_h.NULL(); // Double-check this (normally you shouldn't use a NULL pointer for a null callback)
MemorySegment privKeySeg = arena.allocateFrom(JAVA_BYTE, seckey.getEncoded());
int return_val = secp256k1_h.secp256k1_ecdsa_sign(ctx, sig, msg_hash, privKeySeg, nullCallback, nullPointer);
int return_val = secp256k1_h.secp256k1_ecdsa_sign(ctx, sig, msg_hash, privKeySeg, nonceFpNull, ndataSegment);
privKeySeg.fill((byte) 0x00);
return SecpResult.checked(return_val, () -> EcdsaSignature.of(sig.toArray(JAVA_BYTE)));
}
Expand Down