private static bool VerifySignature(Transaction txFrom, Transaction txTo, int txToInN, ScriptVerify flagScriptVerify)
{
var input = txTo.Inputs[txToInN];
if (input.PrevOut.N >= txFrom.Outputs.Count)
{
return(false);
}
if (input.PrevOut.Hash != txFrom.GetHash())
{
return(false);
}
var output = txFrom.Outputs[input.PrevOut.N];
var txData = new PrecomputedTransactionData(txFrom);
var checker = new TransactionChecker(txTo, txToInN, output.Value, txData);
var ctx = new ScriptEvaluationContext {
ScriptVerify = flagScriptVerify
};
return(ctx.VerifyScript(input.ScriptSig, output.ScriptPubKey, checker));
}
//https://en.bitcoin.it/wiki/OP_CHECKSIG
public static uint256 SignatureHash(Script scriptCode, Transaction txTo, int nIn, SigHash nHashType, Money amount, HashVersion sigversion, PrecomputedTransactionData precomputedTransactionData)
{
if (sigversion == HashVersion.Witness)
{
if (amount == null)
{
throw new ArgumentException("The amount of the output being signed must be provided", "amount");
}
uint256 hashPrevouts = uint256.Zero;
uint256 hashSequence = uint256.Zero;
uint256 hashOutputs = uint256.Zero;
if ((nHashType & SigHash.AnyoneCanPay) == 0)
{
hashPrevouts = precomputedTransactionData == null?
GetHashPrevouts(txTo) : precomputedTransactionData.HashPrevouts;
}
if ((nHashType & SigHash.AnyoneCanPay) == 0 && ((uint)nHashType & 0x1f) != (uint)SigHash.Single && ((uint)nHashType & 0x1f) != (uint)SigHash.None)
{
hashSequence = precomputedTransactionData == null?
GetHashSequence(txTo) : precomputedTransactionData.HashSequence;
}
if (((uint)nHashType & 0x1f) != (uint)SigHash.Single && ((uint)nHashType & 0x1f) != (uint)SigHash.None)
{
hashOutputs = precomputedTransactionData == null?
GetHashOutputs(txTo) : precomputedTransactionData.HashOutputs;
}
else if (((uint)nHashType & 0x1f) == (uint)SigHash.Single && nIn < txTo.Outputs.Count)
{
BitcoinStream ss = CreateHashWriter(sigversion);
ss.ReadWrite(txTo.Outputs[nIn]);
hashOutputs = GetHash(ss);
}
BitcoinStream sss = CreateHashWriter(sigversion);
// Version
sss.ReadWrite(txTo.Version);
// Input prevouts/nSequence (none/all, depending on flags)
sss.ReadWrite(hashPrevouts);
sss.ReadWrite(hashSequence);
// The input being signed (replacing the scriptSig with scriptCode + amount)
// The prevout may already be contained in hashPrevout, and the nSequence
// may already be contain in hashSequence.
sss.ReadWrite(txTo.Inputs[nIn].PrevOut);
sss.ReadWrite(scriptCode);
sss.ReadWrite(amount.Satoshi);
sss.ReadWrite((uint)txTo.Inputs[nIn].Sequence);
// Outputs (none/one/all, depending on flags)
sss.ReadWrite(hashOutputs);
// Locktime
sss.ReadWriteStruct(txTo.LockTime);
// Sighash type
sss.ReadWrite((uint)nHashType);
return(GetHash(sss));
}
if (nIn >= txTo.Inputs.Count)
{
Utils.log("ERROR: SignatureHash() : nIn=" + nIn + " out of range\n");
return(uint256.One);
}
// Check for invalid use of SIGHASH_SINGLE
if (nHashType == SigHash.Single)
{
if (nIn >= txTo.Outputs.Count)
{
Utils.log("ERROR: SignatureHash() : nOut=" + nIn + " out of range\n");
return(uint256.One);
}
}
var scriptCopy = new Script(scriptCode._Script);
scriptCopy.FindAndDelete(OpcodeType.OP_CODESEPARATOR);
var txCopy = new Transaction(txTo.ToBytes());
//Set all TxIn script to empty string
foreach (var txin in txCopy.Inputs)
{
txin.ScriptSig = new Script();
}
//Copy subscript into the txin script you are checking
txCopy.Inputs[nIn].ScriptSig = scriptCopy;
var hashType = nHashType & (SigHash)31;
if (hashType == SigHash.None)
{
//The output of txCopy is set to a vector of zero size.
txCopy.Outputs.Clear();
//All other inputs aside from the current input in txCopy have their nSequence index set to zero
foreach (var input in txCopy.Inputs.Where((x, i) => i != nIn))
{
input.Sequence = 0;
}
}
else if (hashType == SigHash.Single)
{
//The output of txCopy is resized to the size of the current input index+1.
txCopy.Outputs.RemoveRange(nIn + 1, txCopy.Outputs.Count - (nIn + 1));
//All other txCopy outputs aside from the output that is the same as the current input index are set to a blank script and a value of (long) -1.
for (var i = 0; i < txCopy.Outputs.Count; i++)
{
if (i == nIn)
{
continue;
}
txCopy.Outputs[i] = new TxOut();
}
//All other txCopy inputs aside from the current input are set to have an nSequence index of zero.
foreach (var input in txCopy.Inputs.Where((x, i) => i != nIn))
{
input.Sequence = 0;
}
}
if ((nHashType & SigHash.AnyoneCanPay) != 0)
{
//The txCopy input vector is resized to a length of one.
var script = txCopy.Inputs[nIn];
txCopy.Inputs.Clear();
txCopy.Inputs.Add(script);
//The subScript (lead in by its length as a var-integer encoded!) is set as the first and only member of this vector.
txCopy.Inputs[0].ScriptSig = scriptCopy;
}
//Serialize TxCopy, append 4 byte hashtypecode
var stream = CreateHashWriter(sigversion);
txCopy.ReadWrite(stream);
stream.ReadWrite((uint)nHashType);
return(GetHash(stream));
}