Renci.SshNet.Security.Cryptography.Ciphers.RsaCipher.Transform C# (CSharp) Method

        private byte[] Transform(byte[] data, int offset, int length)
        {
            Array.Reverse(data, offset, length);

            var inputBytes = new byte[length + 1];
            Buffer.BlockCopy(data, offset, inputBytes, 0, length);

            var input = new BigInteger(inputBytes);

            BigInteger result;

            if (_isPrivate)
            {
                var random = BigInteger.One;
                var max = _key.Modulus - 1;
                var bitLength = _key.Modulus.BitLength;

                if (max < BigInteger.One)
                    throw new SshException("Invalid RSA key.");

                while (random <= BigInteger.One || random >= max)
                {
                    random = BigInteger.Random(bitLength);
                }

                var blindedInput = BigInteger.PositiveMod((BigInteger.ModPow(random, _key.Exponent, _key.Modulus) * input), _key.Modulus);

                // mP = ((input Mod p) ^ dP)) Mod p
                var mP = BigInteger.ModPow((blindedInput % _key.P), _key.DP, _key.P);

                // mQ = ((input Mod q) ^ dQ)) Mod q
                var mQ = BigInteger.ModPow((blindedInput % _key.Q), _key.DQ, _key.Q);

                var h = BigInteger.PositiveMod(((mP - mQ) * _key.InverseQ), _key.P);

                var m = h * _key.Q + mQ;

                var rInv = BigInteger.ModInverse(random, _key.Modulus);

                result = BigInteger.PositiveMod((m * rInv), _key.Modulus);
            }
            else
            {
                result = BigInteger.ModPow(input, _key.Exponent, _key.Modulus);
            }

            return result.ToByteArray().Reverse();
        }
    }