public static bool TryCreateFromCompact(ReadOnlySpan <byte> in64, int recid, [MaybeNullWhen(false)] out SecpRecoverableECDSASignature sig)
{
sig = null;
if (SecpECDSASignature.TryCreateFromCompact(in64, out var compact) && compact is SecpECDSASignature)
{
sig = new SecpRecoverableECDSASignature(compact, recid);
return(true);
}
return(false);
}
public bool TrySignRecoverable(ReadOnlySpan <byte> msg32, INonceFunction?nonceFunction, out SecpRecoverableECDSASignature?recoverableSignature)
{
if (msg32.Length != 32)
{
throw new ArgumentException(paramName: nameof(msg32), message: "msg32 should be 32 bytes");
}
if (this.TrySignECDSA(msg32, nonceFunction, out int recid, out SecpECDSASignature? sig) && sig is SecpECDSASignature)
{
recoverableSignature = new SecpRecoverableECDSASignature(sig, recid);
return(true);
}
recoverableSignature = null;
return(false);
}
public byte[] SignCompact(uint256 hash, bool forceLowR)
{
if (hash is null)
{
throw new ArgumentNullException(nameof(hash));
}
AssertNotDisposed();
#if HAS_SPAN
Span <byte> vchSig = stackalloc byte[65];
int rec = -1;
var sig = new Secp256k1.SecpRecoverableECDSASignature(_ECKey.Sign(hash, forceLowR, out rec), rec);
sig.WriteToSpanCompact(vchSig.Slice(1), out int recid);
vchSig[0] = (byte)(27 + rec + (IsCompressed ? 4 : 0));
return(vchSig.ToArray());
#else
var sig = _ECKey.Sign(hash, forceLowR);
// Now we have to work backwards to figure out the recId needed to recover the signature.
int recId = -1;
for (int i = 0; i < 4; i++)
{
ECKey k = ECKey.RecoverFromSignature(i, sig, hash, IsCompressed);
if (k != null && k.GetPubKey(IsCompressed).ToHex() == PubKey.ToHex())
{
recId = i;
break;
}
}
if (recId == -1)
{
throw new InvalidOperationException("Could not construct a recoverable key. This should never happen.");
}
int headerByte = recId + 27 + (IsCompressed ? 4 : 0);
byte[] sigData = new byte[65]; // 1 header + 32 bytes for R + 32 bytes for S
sigData[0] = (byte)headerByte;
#pragma warning disable 618
Array.Copy(Utils.BigIntegerToBytes(sig.R, 32), 0, sigData, 1, 32);
Array.Copy(Utils.BigIntegerToBytes(sig.S, 32), 0, sigData, 33, 32);
#pragma warning restore 618
return(sigData);
#endif
}
