cryptoSecretBoxOpenEasy method

Uint8List cryptoSecretBoxOpenEasy(Uint8List ciphertext, Uint8List nonce, Uint8List sharedKey)

Implementation

Uint8List cryptoSecretBoxOpenEasy(
  Uint8List ciphertext,
  Uint8List nonce,
  Uint8List sharedKey,
) {
  final plaintextLength = ciphertext.length - crypto_secretbox_MACBYTES;
  final ciphertextPointer = calloc<ffi.Uint8>(ciphertext.length);
  final plaintextPointer = calloc<ffi.Uint8>(plaintextLength);
  final noncePointer = calloc<ffi.Uint8>(crypto_secretbox_NONCEBYTES);
  final sharedKeyPointer = calloc<ffi.Uint8>(crypto_secretbox_KEYBYTES);

  // Fill nonce, secretKey, and ciphertext with appropriate values
  for (var i = 0; i < ciphertext.length; i++) {
    ciphertextPointer.elementAt(i).value = ciphertext[i];
  }
  for (var i = 0; i < nonce.length; i++) {
    noncePointer.elementAt(i).value = nonce[i];
  }
  for (var i = 0; i < sharedKey.length; i++) {
    sharedKeyPointer.elementAt(i).value = sharedKey[i];
  }

  try {
    // Call crypto_secretbox_open_easy to decrypt the message
    final result = crypto_secretbox_open_easy(
      plaintextPointer.cast<ffi.UnsignedChar>(),
      ciphertextPointer.cast<ffi.UnsignedChar>(),
      ciphertext.length,
      noncePointer.cast<ffi.UnsignedChar>(),
      sharedKeyPointer.cast<ffi.UnsignedChar>(),
    );

    if (result == 0) {
      final plaintextList = plaintextPointer
          .asTypedList(ciphertext.length - crypto_secretbox_MACBYTES);
      // Clone the original list
      return Uint8List.fromList(List.from(plaintextList));
    } else {
      debugPrint('[Lazysodium] Crypto secret box open easy failed.');
      return Uint8List(0);
    }
  } finally {
    // Free allocated memory
    calloc.free(ciphertextPointer);
    calloc.free(plaintextPointer);
    calloc.free(noncePointer);
    calloc.free(sharedKeyPointer);
  }
}