cryptoStreamChaCha20Xor method

Uint8List cryptoStreamChaCha20Xor(Uint8List message, Uint8List nonce, Uint8List key)

Implementation

Uint8List cryptoStreamChaCha20Xor(
  Uint8List message,
  Uint8List nonce,
  Uint8List key,
) {
  // Allocate memory for the output stream (ciphertext), nonce (n), and key (k)
  final ciphertextPointer = calloc<ffi.Uint8>(message.length);
  final plaintextPointer = calloc<ffi.Uint8>(message.length);
  final noncePointer = calloc<ffi.Uint8>(nonce.length);
  final keyPointer = calloc<ffi.Uint8>(crypto_stream_chacha20_KEYBYTES);

  try {
    // Fill the nonce and key with your values
    for (var i = 0; i < nonce.length; i++) {
      noncePointer.elementAt(i).value = nonce[i];
    }
    for (var i = 0; i < key.length; i++) {
      keyPointer.elementAt(i).value = key[i];
    }
    for (var i = 0; i < message.length; i++) {
      plaintextPointer.elementAt(i).value = message[i];
    }

    // Call crypto_stream_chacha20 to generate the stream
    final result = crypto_stream_chacha20_xor(
      ciphertextPointer.cast<ffi.UnsignedChar>(),
      plaintextPointer.cast<ffi.UnsignedChar>(),
      message.length,
      noncePointer.cast<ffi.UnsignedChar>(),
      keyPointer.cast<ffi.UnsignedChar>(),
    );

    if (result == 0) {
      final ciphertextList = ciphertextPointer.asTypedList(message.length);
      // Clone the original list
      return Uint8List.fromList(List.from(ciphertextList));
    } else {
      debugPrint('[Lazysodium] Crypto stream ChaCha20 failed.');
      return Uint8List(0);
    }
  } finally {
    // Free allocated memory
    calloc.free(ciphertextPointer);
    calloc.free(plaintextPointer);
    calloc.free(noncePointer);
    calloc.free(keyPointer);
  }
}