public IntegerPolynomial createMsgRep(byte[] msgHash, int r)
{
int N = param.N;
int q = param.q;
int c = 31 - IntUtils.numberOfLeadingZeros(q);
int B = (c + 7) / 8;
IntegerPolynomial i = new IntegerPolynomial(N);
MemoryStream cbuf = new MemoryStream(msgHash.Length + 4);
BinaryWriter bwr = new BinaryWriter(cbuf);
bwr.Write(msgHash);
bwr.Write(r);
Prng prng = new Prng(cbuf.ToArray(), param.hashAlg);
for (int t = 0; t < N; t++)
{
byte[] o = prng.nextBytes(B);
int hi = o[o.Length - 1];
hi >>= 8 * B - c;
hi <<= 8 * B - c;
o[o.Length - 1] = (byte)hi;
MemoryStream obuf = new MemoryStream(4);
BinaryWriter bwr2 = new BinaryWriter(obuf);
bwr2.Write(o);
obuf.Position = 0;
// reverse byte order so it matches the endianness of java ints
i.Coeffs[t] = ArrayUtils.ReverseBytes(obuf.ToArray());
}
return(i);
}
/**
* Returns the length of a signature made with this parameter set.<br/>
* The length does not depend on the message size.
* @return the length in bytes
*/
public int getOutputLength()
{
int logq = 32 - IntUtils.numberOfLeadingZeros(q - 1); // ceil(log q)
int polyLen = (N * logq + 7) / 8; // length of a polynomial in bytes
return(polyLen + 4); // add 4 for the retry count
}