public BigInteger[] GenerateSignature(byte[] message)
{
if (privateKey == null) throw new InvalidOperationException();
BigInteger e = CalculateE(curve.N, message);
BigInteger d = new BigInteger(privateKey.Reverse().Concat(new byte[1]).ToArray());
BigInteger r, s;
using (RNGCryptoServiceProvider rng = new RNGCryptoServiceProvider())
{
do
{
BigInteger k;
do
{
do
{
k = rng.NextBigInteger(curve.N.GetBitLength());
}
while (k.Sign == 0 || k.CompareTo(curve.N) >= 0);
ECPoint p = ECPoint.Multiply(curve.G, k);
BigInteger x = p.X.Value;
r = x.Mod(curve.N);
}
while (r.Sign == 0);
s = (k.ModInverse(curve.N) * (e + d * r)).Mod(curve.N);
if (s > curve.N / 2)
{
s = curve.N - s;
}
}
while (s.Sign == 0);
}
return new BigInteger[] { r, s };
}
