AaltoTLS.PluginInterface.GenericCbcModeCryptoTransform.TransformBlock C# (CSharp) Method

        public int TransformBlock(byte[] inputBuffer,
		                          int inputOffset,
		                          int inputCount,
		                          byte[] outputBuffer,
		                          int outputOffset)
        {
            if (_disposed) {
                throw new ObjectDisposedException(GetType().FullName);
            }

            if (inputBuffer == null)
                throw new ArgumentNullException("inputBuffer");
            if (inputOffset < 0 || inputOffset >= inputBuffer.Length)
                throw new ArgumentOutOfRangeException("inputOffset");
            if (inputCount < 0 || inputCount > inputBuffer.Length-inputOffset)
                throw new ArgumentOutOfRangeException("inputCount");
            if (inputCount % _blockSize != 0)
                throw new CryptographicException("inputCount");
            if (outputBuffer == null)
                throw new ArgumentNullException("outputBuffer");
            if (outputOffset < 0 || outputOffset > outputBuffer.Length-inputCount)
                throw new ArgumentOutOfRangeException("outputOffset");

            // This is manual CBC handling
            for (int i=0; i<inputCount; i+=_blockSize) {
                if (_encrypting) {
                    for (int j=0; j<_blockSize; j++) {
                        _currentIV[j] ^= inputBuffer[inputOffset+i+j];
                    }
                    _cipher.Encrypt(_currentIV, 0, outputBuffer, outputOffset+i);
                    Array.Copy(outputBuffer, outputOffset+i, _currentIV, 0, _blockSize);
                } else {
                    _cipher.Decrypt(inputBuffer, inputOffset+i, outputBuffer, outputOffset+i);
                    for (int j=0; j<_blockSize; j++) {
                        outputBuffer[outputOffset+i+j] ^= _currentIV[j];
                    }
                    Array.Copy(inputBuffer, inputOffset+i, _currentIV, 0, _blockSize);
                }
            }

            return inputCount;
        }