/// <summary>
/// Signs the given transaction with the given private key.
/// </summary>
/// <param name="transaction"></param>
/// <param name="txInIndex"></param>
/// <param name="privateKey"></param>
/// <param name="unspentTxOuts"></param>
/// <returns></returns>
public string SignTxIn(Transaction transaction, int txInIndex, string privateKey, IList <UnspentTxOut> unspentTxOuts)
{
TxIn txIn = transaction.TxIns[txInIndex];
string dataToSign = transaction.Id;
UnspentTxOut referencedUnspentTxOut = FindUnspentTxOut(txIn.TxOutId, txIn.TxOutIndex, unspentTxOuts);
if (referencedUnspentTxOut == null)
{
this.logger.LogCritical("Could not find referenced txOut");
throw new InvalidOperationException("Could not find referenced txOut");
}
string referencedAddress = referencedUnspentTxOut.Address;
if (Crypto.GetPublicKey(privateKey) != referencedAddress)
{
this.logger.LogCritical("Trying to sign an input with private key that does not match the address that is referenced in txIn.");
throw new InvalidOperationException("Trying to sign an input with private key that does not match the address that is referenced in txIn.");
}
string signature = Crypto.GetSignature(dataToSign, privateKey);
return(signature);
}
private bool IsValidTxIn(TxIn txIn, Transaction transaction, IList <UnspentTxOut> unspentTxOuts)
{
UnspentTxOut referencedUnspentTxOut = unspentTxOuts
.FirstOrDefault(uTxOut => uTxOut.TxOutId == txIn.TxOutId && uTxOut.TxOutIndex == txIn.TxOutIndex);
if (referencedUnspentTxOut == null)
{
this.logger.LogError($"Referenced txOut not found: {JsonConvert.SerializeObject(txIn)}");
return(false);
}
string address = referencedUnspentTxOut.Address;
bool isValidSignature = Crypto.VerifySignature(address, transaction.Id, txIn.Signature);
if (!isValidSignature)
{
this.logger.LogError($"Invalid txIn signature: {txIn.Signature} txId: {transaction.Id} address: {address}");
return(false);
}
return(true);
}