/// <summary>
/// Signs given data and returns the r and s components of the ECDSA signature, along with a recovery ID to recover the public key given the original signed message and the returned components.
/// </summary>
/// <param name="hash">The hash to be signed.</param>
/// <returns>Returns r and s components of an ECDSA signature, along with a recovery ID to recover the signers public key given the original signed message and r, s.</returns>
public override (byte RecoveryID, BigInteger r, BigInteger s) SignData(Span <byte> hash)
{
// Verify we have a private key.
if (KeyType != EthereumEcdsaKeyType.Private)
{
throw _notPrivateKeyException;
}
// Initialize our crypto provider.
ECDsaSigner signer = new ECDsaSigner();
signer.Init(true, PrivateKey);
// Obtain our signature, rs[0] ("r") and rs[1] ("s")
Org.BouncyCastle.Math.BigInteger[] rs = signer.GenerateSignature(hash.ToArray());
// We want to make sure we enforce a low S value
rs[1] = Secp256k1Curve.EnforceLowS(rs[1]);
// We need to return a valid recovery ID for this signature. We do this by trying all of our 4 possible recovery IDs to make sure the public key hash recovered is the same as ours.
// We start by obtaining our current public key hash
byte[] actualPublicKeyHash = GetPublicKeyHash();
// Next we try of our potential recovery IDs until we can obtain the matching public key from the signature.
// 2, 3 are usually not used and 0, 1 denote odd or even Y, which can be figured out.
for (byte recoveryID = 0; recoveryID < 4; recoveryID++)
{
// We wrap this in a try in case, as we know one of these IDs will work.
try
{
EthereumEcdsa possibleMatch = Recover(hash, recoveryID, rs[0].ToNumericsBigInteger(), rs[1].ToNumericsBigInteger());
if (actualPublicKeyHash.ValuesEqual(possibleMatch.GetPublicKeyHash()))
{
return(recoveryID, rs[0].ToNumericsBigInteger(), rs[1].ToNumericsBigInteger());
static EthereumEcdsaBouncyCastle GenerateSingle(uint accountIndex, IAccountDerivation accountFactory)
{
var privateKey = accountFactory.GeneratePrivateKey(accountIndex);
var keyBigInt = BigIntegerConverter.GetBigInteger(privateKey, signed: false, byteCount: PRIVATE_KEY_SIZE);
keyBigInt = Secp256k1Curve.EnforceLowS(keyBigInt);
// Return our private key instance.
return(new EthereumEcdsaBouncyCastle(privateKey, EthereumEcdsaKeyType.Private));
}
static EthereumEcdsaNative Generate(uint accountIndex, Secp256k1 secp256k1, IAccountDerivation accountFactory)
{
var privateKey = accountFactory.GeneratePrivateKey(accountIndex);
if (!secp256k1.SecretKeyVerify(privateKey))
{
var errMsg = "Unmanaged EC library failed to valid private key. ";
if (IncludeKeyDataInExceptions)
{
errMsg += $"Private key: {privateKey.ToHexString()}";
}
throw new Exception(errMsg);
}
var keyBigInt = BigIntegerConverter.GetBigInteger(privateKey, signed: false, byteCount: PRIVATE_KEY_SIZE);
keyBigInt = Secp256k1Curve.EnforceLowS(keyBigInt);
privateKey = BigIntegerConverter.GetBytes(keyBigInt, PRIVATE_KEY_SIZE);
return(new EthereumEcdsaNative(privateKey, EthereumEcdsaKeyType.Private));
}
