private BouncyCastle.FpFieldElement GetX(
byte[] input,
BouncyCastle.FpCurve curve,
int index,
int counter)
{
int numIterations = (int)System.Math.Ceiling(
(double)(curve.Q.BitLength / 8) / (double)hashByteSize);
byte[] digest = new byte[numIterations * hashByteSize];
for (int iteration = 0; iteration < numIterations; iteration++)
{
byte[] hashInput = ProtocolHelper.Concatenate(
input,
encoding.GetBytes(
index.ToString() + counter.ToString() + iteration.ToString()));
hash.HashWithoutFormatting(hashInput);
Array.Copy(hash.Digest, 0, digest, hashByteSize * iteration, hashByteSize);
}
BCBigInt x = new BCBigInt(1, digest).Mod(curve.Q);
return(curve.FromBigInteger(x) as BouncyCastle.FpFieldElement);
}
