public virtual BigInteger ProcessBlock(BigInteger input) { if (key == null) { throw new InvalidOperationException("RSA engine not initialised"); } // BigInteger input = core.ConvertInput(inBuf, inOff, inLen); BigInteger result; if (key is RsaPrivateCrtKeyParameters) { RsaPrivateCrtKeyParameters k = (RsaPrivateCrtKeyParameters)key; BigInteger e = k.PublicExponent; if (e != null) // can't do blinding without a public exponent { BigInteger m = k.Modulus; BigInteger r = BigIntegers.CreateRandomInRange( BigInteger.One, m.Subtract(BigInteger.One), random); BigInteger blindedInput = r.ModPow(e, m).Multiply(input).Mod(m); BigInteger blindedResult = core.ProcessBlock(blindedInput); BigInteger rInv = r.ModInverse(m); result = blindedResult.Multiply(rInv).Mod(m); // defence against Arjen Lenstra�s CRT attack if (!input.Equals(result.ModPow(e, m))) { throw new InvalidOperationException("RSA engine faulty decryption/signing detected"); } } else { result = core.ProcessBlock(input); } } else { result = core.ProcessBlock(input); } return(result); }
/** * Process a single block using the basic RSA algorithm. * * @param inBuf the input array. * @param inOff the offset into the input buffer where the data starts. * @param inLen the length of the data to be processed. * @return the result of the RSA process. * @exception DataLengthException the input block is too large. */ public byte[] ProcessBlock( byte[] inBuf, int inOff, int inLen) { if (core == null) { throw new InvalidOperationException("RSA engine not initialised"); } return(core.ConvertOutput(core.ProcessBlock(core.ConvertInput(inBuf, inOff, inLen)))); }