/// <summary>
/// Implement the ICryptoTransform method.
/// </summary>
public int TransformBlock(byte[] inputBuffer, int inputOffset, int inputCount, byte[] outputBuffer, int outputOffset)
{
// Pass the data stream to the hash algorithm for generating the Auth Code.
// This does not change the inputBuffer. Do this before decryption for read mode.
if (!_writeMode)
{
#if NET45
_hmacsha1.TransformBlock(inputBuffer, inputOffset, inputCount, inputBuffer, inputOffset);
#elif NETSTANDARD1_3
_hmacsha1.AppendData(inputBuffer);
#endif
}
// Encrypt with AES in CTR mode. Regards to Dr Brian Gladman for this.
int ix = 0;
while (ix < inputCount)
{
if (_encrPos == ENCRYPT_BLOCK)
{
/* increment encryption nonce */
int j = 0;
while (++_counterNonce[j] == 0)
{
++j;
}
/* encrypt the nonce to form next xor buffer */
_encryptor.TransformBlock(_counterNonce, 0, _blockSize, _encryptBuffer, 0);
_encrPos = 0;
}
outputBuffer[ix + outputOffset] = (byte)(inputBuffer[ix + inputOffset] ^ _encryptBuffer[_encrPos++]);
//
ix++;
}
if (_writeMode)
{
// This does not change the buffer.
#if NET45
_hmacsha1.TransformBlock(outputBuffer, outputOffset, inputCount, outputBuffer, outputOffset);
#elif NETSTANDARD1_3
_hmacsha1.AppendData(outputBuffer);
#endif
}
return(inputCount);
}