public static bool RsaOTDecrypt(ref byte[] buffer, int position, int length)
{
if (length - position != 128)
return false;
byte[] temp = new byte[128];
Array.Copy(buffer, position, temp, 0, 128);
BigInteger input = new BigInteger(temp);
BigInteger output;
BigInteger m1 = input.modPow(otServerDP, otServerP);
// m2 = c^dq mod q
BigInteger m2 = input.modPow(otServerDQ, otServerQ);
BigInteger h;
if (m2 > m1)
{
// thanks to benm!
h = otServerP - ((m2 - m1) * otServerInverseQ % otServerP);
output = m2 + otServerQ * h;
}
else
{
// h = (m1 - m2) * qInv mod p
h = (m1 - m2) * otServerInverseQ % otServerP;
// m = m2 + q * h;
output = m2 + otServerQ * h;
}
Array.Copy(GetPaddedValue(output), 0, buffer, position, 128);
return true;
}
public static bool RsaEncrypt(BigInteger e, BigInteger m, ref byte[] buffer, int position)
{
byte[] temp = new byte[128];
Array.Copy(buffer, position, temp, 0, 128);
BigInteger input = new BigInteger(temp);
BigInteger output = input.modPow(e, m);
// it's sometimes possible for the results to be a byte short
// and this can break some software so we 0x00 pad the result
Array.Copy(GetPaddedValue(output), 0, buffer, position, 128);
return true;
}
