BCrypt.Net.BCrypt.Encipher C# (CSharp) Method

        private void Encipher(uint[] blockArray, int offset)
        {
            uint round,
                     n,
                     block = blockArray[offset],
                     r = blockArray[offset + 1];

            block ^= _P[0];
            unchecked
            {
                for (round = 0; round <= BLOWFISH_NUM_ROUNDS - 2; )
                {
                    // Feistel substitution on left word
                    n = _S[(block >> 24) & 0xff];
                    n += _S[0x100 | ((block >> 16) & 0xff)];
                    n ^= _S[0x200 | ((block >> 8) & 0xff)];
                    n += _S[0x300 | (block & 0xff)];
                    r ^= n ^ _P[++round];

                    // Feistel substitution on right word
                    n = _S[(r >> 24) & 0xff];
                    n += _S[0x100 | ((r >> 16) & 0xff)];
                    n ^= _S[0x200 | ((r >> 8) & 0xff)];
                    n += _S[0x300 | (r & 0xff)];
                    block ^= n ^ _P[++round];
                }
                blockArray[offset] = r ^ _P[BLOWFISH_NUM_ROUNDS + 1];
                blockArray[offset + 1] = block;
            }
        }