processBytes method

@override int processBytes(Uint8List inp, int inpOff, int len, Uint8List out, int outOff,)

Process len bytes from inp starting at offset inpOff and output the result to out at offset outOff.

Returns the number of bytes written to the output.

Implementation

@override
int processBytes(
    Uint8List inp, int inpOff, int len, Uint8List out, int outOff) {
  if (len == 0) return 0;

  if (forEncryption) {
    // all bytes are plain text bytes
    return _processCipherBytes(inp, inpOff, len, out, outOff);
  }

  // last macSize bytes are possibly mac bytes and not cipher text bytes
  // -> keep them in buffer
  var cipherLen = _lastMacSizeBytesOff + len - macSize;

  var resultLen = 0;

  if (cipherLen > 0 && _lastMacSizeBytesOff > 0) {
    // at least part of the buffer are actually cipher text bytes
    // process them and update the buffer

    var l = min(_lastMacSizeBytesOff, cipherLen);
    resultLen += _processCipherBytes(_lastMacSizeBytes!, 0,
        min(_lastMacSizeBytesOff, cipherLen), out, outOff);
    outOff += resultLen;
    cipherLen -= l;
    _lastMacSizeBytes!.setRange(0, macSize - l, _lastMacSizeBytes!.skip(l));
    _lastMacSizeBytesOff -= l;
  }

  if (cipherLen > 0) {
    // part of the input are cipher text bytes
    resultLen += _processCipherBytes(inp, inpOff, cipherLen, out, outOff);
  }

  _lastMacSizeBytes!.setRange(_lastMacSizeBytesOff,
      _lastMacSizeBytesOff + len - cipherLen, inp.skip(inpOff + cipherLen));
  _lastMacSizeBytesOff += len - cipherLen;

  return resultLen;
}