decryptCborPhrase function

Future<String> decryptCborPhrase(List<int> bytes, String password)

Implementation

Future<String> decryptCborPhrase(List<int> bytes, String password) async {
  final recover = Map<String, dynamic>.from(cborDecode(bytes));
  final Uint8List ciphertext = Uint8List.fromList(recover['ciphertext']);
  final Uint8List iv = Uint8List.fromList(recover['cipherparams']['iv']);
  final kdfparams = Map<String, dynamic>.from(cborDecode(recover['kdfparams']));

  final List<int> encodedPassword = utf8.encode(password);
  final derivator = getDerivedKey(
      (Uint8List.fromList(recover['kdf'])).u8aToString(), kdfparams);
  final List<int> derivedKey = derivator.deriveKey(encodedPassword);
  final List<int> macBuffer =
      derivedKey.sublist(16, 32) + ciphertext + iv + ALGO_IDENTIFIER.codeUnits;

  final Uint8List mac = SHA256()
      .update(Uint8List.fromList(derivedKey))
      .update(macBuffer)
      .digest();

  final Uint8List macFromRecover =
      Uint8List.fromList(u8aToU8a((recover['mac'] as List).map((ele) {
    return int.parse(ele.toString());
  }).toList()));

  if (!u8aEq(mac, macFromRecover)) {
    throw 'Decryption Failed';
  }

  final List<int> aesKey = derivedKey.sublist(0, 16);
  final Uint8List encryptedPhrase = Uint8List.fromList(recover['ciphertext']);

  final CTRStreamCipher aes = _initCipher(false, aesKey, iv);

  final Uint8List privateKeyByte = aes.process(encryptedPhrase);
  return privateKeyByte.u8aToString();
}