/// <summary>
/// Creates a signature using ECDSA based on Standards for Efficient Cryptography (SEC 1: Elliptic Curve Cryptography)
/// section 4.1.3 Signing Operation (page 44) with a low s (<<see cref="IECurveFp.N"/>) and
/// low r (DER encoding of it will be <= 32 bytes)
/// </summary>
/// <param name="hash">Hash(m) to use for signing</param>
/// <param name="key">Private key bytes (must be padded to 32 bytes)</param>
/// <returns>Signature</returns>
public Signature Sign(byte[] hash, byte[] key)
{
using Rfc6979 kGen = new Rfc6979();
if (TrySign(hash, key, kGen.GetK(hash, key, null), true, true, out Signature sig))
{
return(sig);
}
else
{
uint count = 1;
byte[] extraEntropy = new byte[32];
do
{
extraEntropy[0] = (byte)count;
extraEntropy[1] = (byte)(count >> 8);
extraEntropy[2] = (byte)(count >> 16);
extraEntropy[3] = (byte)(count >> 24);
count++;
} while (!TrySign(hash, key, kGen.GetK(hash, key, extraEntropy), true, true, out sig));
return(sig);
}
}
public void GetK_RFCTest2()
{
BigInteger order =
BigInteger.Parse("00FFFFFFFF00000000FFFFFFFFFFFFFFFFBCE6FAADA7179E84F3B9CAC2FC632551", NumberStyles.HexNumber);
byte[] data = Helper.HexToBytes("9f86d081884c7d659a2feaa0c55ad015a3bf4f1b2b0b822cd15d6c15b0f00a08");
byte[] keyBytes = Helper.HexToBytes("C9AFA9D845BA75166B5C215767B1D6934E50C3DB36E89B127B8A622B120F6721");
using Rfc6979 rfc = new Rfc6979(order);
BigInteger actual = rfc.GetK(data, keyBytes, null);
BigInteger expected = BigInteger.Parse("00D16B6AE827F17175E040871A1C7EC3500192C4C92677336EC2537ACAEE0008E0", NumberStyles.HexNumber);
Assert.Equal(expected, actual);
}
public void GetK_RFCTest1()
{
BigInteger order =
BigInteger.Parse("00FFFFFFFF00000000FFFFFFFFFFFFFFFFBCE6FAADA7179E84F3B9CAC2FC632551", NumberStyles.HexNumber);
byte[] data = Helper.HexToBytes("AF2BDBE1AA9B6EC1E2ADE1D694F41FC71A831D0268E9891562113D8A62ADD1BF");
byte[] keyBytes = Helper.HexToBytes("C9AFA9D845BA75166B5C215767B1D6934E50C3DB36E89B127B8A622B120F6721");
using Rfc6979 rfc = new Rfc6979(order);
BigInteger actual = rfc.GetK(data, keyBytes, null);
BigInteger expected = BigInteger.Parse("00A6E3C57DD01ABE90086538398355DD4C3B17AA873382B0F24D6129493D8AAD60", NumberStyles.HexNumber);
Assert.Equal(expected, actual);
}