// seed PRNG with r'
sr0.addSeedMaterial(rPrime);
// generate random sequence R(r') ...
byte[] mConstPrime = new byte[c1Len];
sr0.nextBytes(mConstPrime);
// ... and XOR with c1 to obtain (m||const')
for (int i = c1Len - 1; i >= 0; i--)
{
mConstPrime[i] ^= c1[i];