我如何签署一个TransactionHex与SeedHex使用secp256k1在c#与弹性城堡? &

Question

我有这个nodejs片段，我想在c#中实现。SignTransaction函数接受一个seedHex字符串(长度:64)和一个TransactionHex字符串，使用secp256k1算法创建签名并附加到TransactionHex的末尾。

const sha256 = require('sha256');
const EC = require('elliptic').ec;
const ec = new EC("secp256k1");
// Serialize a number into an 8-byte array. This is a copy/paste primitive, not worth
// getting into the details.
function uvarint64ToBuf (uint) {
const result = [];
while (uint >= 0x80) {
result.push((uint & 0xFF) | 0x80);
uint >>>= 7;
}
result.push(uint | 0);
return new Buffer(result);
}
// Sign transaction with seed
function signTransaction (seed, txnHex) {
const privateKey = ec.keyFromPrivate(seed);
const transactionBytes = new Buffer(txnHex, 'hex');
const transactionHash = new Buffer(sha256.x2(transactionBytes), 'hex');
const signature = privateKey.sign(transactionHash);
const signatureBytes = new Buffer(signature.toDER());
const signatureLength = uvarint64ToBuf(signatureBytes.length);
const signedTransactionBytes = Buffer.concat([
transactionBytes.slice(0, -1),
signatureLength,
signatureBytes
])
return signedTransactionBytes.toString('hex');
}

示例事务hex

01efa5060f5fdae5ed9d90e5f076b2c328a64e347d0c87e8e3317daec5a44fe7c8000102bd53e48625f49e60ff6b7a934e3871b54cc2a93a8737352e8320549e42e2322bab0405270000167b22426f6479223a2248656c6c6f20576f726c64227de807d461f4df9efad8a0f3f716002102bd53e48625f49e60ff6b7a934e3871b54cc2a93a8737352e8320549e42e2322b0000

示例签名事务十六进制从javascript函数返回

01efa5060f5fdae5ed9d90e5f076b2c328a64e347d0c87e8e3317daec5a44fe7c8000102bd53e48625f49e60ff6b7a934e3871b54cc2a93a8737352e8320549e42e2322bab0405270000167b22426f6479223a2248656c6c6f20576f726c64227de807d461f4df9efad8a0f3f716002102bd53e48625f49e60ff6b7a934e3871b54cc2a93a8737352e8320549e42e2322b00473045022100c36e2b80f2160304cf640b1296244e7a3873aacf2831098bca3727ad06f4c270022007d3697ceef266a05ad70219d92fbd570f6ec7a5731aaf02718213067d42d1cf

如果你注意到十六进制符号是TransactionHex + 47 (length of signature) + 473045022100c36e2b80f2160304cf640b1296244e7a3873aacf2831098bca3727ad06f4c270022007d3697ceef266a05ad70219d92fbd570f6ec7a5731aaf02718213067d42d1cf (actual signature)

我试图在Unity3d中使用c# Bouncy Castle库来生成签名部分，但没有成功。

这是c#代码(源代码)

public string GetSignature(string privateKey, string message)
{
var curve = SecNamedCurves.GetByName("secp256k1");
var domain = new ECDomainParameters(curve.Curve, curve.G, curve.N, curve.H);
var keyParameters = new ECPrivateKeyParameters(new BigInteger(privateKey, 16), domain);
var signer = new ECDsaSigner(new HMacDsaKCalculator(new Sha256Digest()));
signer.Init(true, keyParameters);
var signature = signer.GenerateSignature(Encoding.UTF8.GetBytes(message));
var r = signature[0];
var s = signature[1];
var otherS = curve.Curve.Order.Subtract(s);
if (s.CompareTo(otherS) == 1)
{
s = otherS;
}
var derSignature = new DerSequence
(
new DerInteger(new BigInteger(1, r.ToByteArray())),
new DerInteger(new BigInteger(1, s.ToByteArray()))
)
.GetDerEncoded();
return Convert(derSignature);
}
public string Convert(byte[] input)
{
return string.Concat(input.Select(x => x.ToString("x2")));
}
public byte[] Convert(string input)
{
if (input.StartsWith("0x")) input = input.Remove(0, 2);
return Enumerable.Range(0, input.Length / 2).Select(x => System.Convert.ToByte(input.Substring(x * 2, 2), 16)).ToArray();
}

这确实会生成一个签名，但它与我上面提到的不相同。

GetSignature生成的签名

3044022018a06b1f2b8a1e2f5ea2a78b0d6d98ec483b9fa4345821cfef892be6c825ff4702207958160e533c801dff5e50600206e1cd938d6df74ebfa4b0347a95de67dda986

注:下面是python等价的事务签名，以供参考。

Answer 1

NodeJS代码中的sha256.x2()哈希两次，而c#代码中的ECDsaSigner根本不哈希。因此，在c#代码中，GetSignature()必须显式散列两次:

using Org.BouncyCastle.Crypto.Digests;
...
var messageBytes = Convert(message);
var hash = GetHash(GetHash(messageBytes));
var signature = signer.GenerateSignature(hash);
...

private static byte[] GetHash(byte[] data)
{
var digest = new Sha256Digest();
var hash = new byte[digest.GetDigestSize()];
digest.BlockUpdate(data, 0, data.Length);
digest.DoFinal(hash, 0);
return hash;
}

由于两种代码都使用了RFC6979规定的确定性ECDSA算法，因此相同输入数据的哈希值是相同的，可以进行比较。

总体结果是没有最后一个字节的txnHex，签名的十六进制编码长度和ASN.1/DER格式的签名的连接;一个可能的实现是:

var txnHex = "...";
var seed = "...";
string signature = GetSignature(seed, txnHex);
string signedTransactionBytes = txnHex.Substring(0, txnHex.Length - 2) + (signature.Length / 2).ToString("x") + signature;

请注意，uvarint64ToBuf()的实现实际上更复杂，但对于这里使用的签名长度可以简化。