CODEWITHSUNDEEP
dartencryptioncryptographyaes
Ουιλιαμ Αρκευα
Ουιλιαμ Αρκευα

Reputation: 6257

Problem when encrypting/decrypting by using Encrypt package

I have these PostgreSQL commands:

select encrypt_iv('test1','테스트2','测试3','aes-cbc');
select convert_from(decrypt_iv('\x8e9a657e13b64f4111ab1668dc0f5747','테스트2','测试3','aes-cbc'),'SQL_ASCII');

I'm trying to reproduce those commands in Dart by using Encrypt package:

void main(List<String> args) {
  final plainText = 'test1';

  final key = Key.fromUtf8('테스트2');
  final iv = IV.fromUtf8('测试3');
  final encrypter = Encrypter(AES(key, mode: AESMode.cbc));

  final encrypted = encrypter.encrypt(plainText, iv: iv);
  final decrypted = encrypter.decrypt(encrypted, iv: iv);

  print(decrypted);
  print(encrypted.bytes);
  print(encrypted.base16);
  print(encrypted.base64);  
}

I'm getting this error message:

Unhandled exception:
Invalid argument(s): Initialization vector must be the same length as block size
#0      CBCBlockCipher.init (package:pointycastle/block/modes/cbc.dart:52:7)
#1      PaddedBlockCipherImpl.init (package:pointycastle/padded_block_cipher/padded_block_cipher_impl.dart:47:12)
#2      AES.encrypt (package:encrypt/src/algorithms/aes.dart:35:9)
#3      Encrypter.encryptBytes (package:encrypt/src/encrypter.dart:12:19)
#4      Encrypter.encrypt (package:encrypt/src/encrypter.dart:20:12)
#5      main (file:///home/userx/Projects/dart/encrypt_example/bin/main.dart:11:31)
#6      _delayEntrypointInvocation.<anonymous closure> (dart:isolate-patch/isolate_patch.dart:281:32)
#7      _RawReceivePortImpl._handleMessage (dart:isolate-patch/isolate_patch.dart:184:12)

Help is missing in this package so I don't know how to properly use it.

Can someone give me some guidance on its use or suggest another package for that purpose?

Upvotes: 0

Views: 1526

Answers (1)

gusto2
gusto2

Reputation: 12085

Initialization vector must be the same length as block size

AES block size is 128 bit (16 bytes), therefore

  • IV must be 16 bytes long
  • AES key must be 128, 192 or 256 bits long (16, 24 or 32 bytes) based on the algorithm used

The PostgreSQL documentation claims for IV:

It is clipped or padded with zeroes if not exactly block size.

I assume (!) it will be the same for the key. IMHO this is a terrible idea from security and interoperability perspective), but we have to live with it. So try to have a zero-byte array of required length and copy your shorter IV or key to the array.

Next

  • IV must be random and unpredictable for the cbc mode to be safe, usually stored along (next to) the cipthertext
  • You may hit another issue, but basically you need to get all parameters right - aes-size, key, iv, mode of encryption

Upvotes: 2

Related Questions