RSA encrypted with dart doesn't match with PHP

[zerocoll9]

I tried to encrypt a string in dart with Encrypt, but, when i compared it with that openssl on php gave me, it didn't match. I tried every padding avaible.

[leocavalcante]

Can you share a snippet with this issue, please?

[zerocoll9]

Well, th Dart code was in example, and i used the same key since my keys doesn't worked , i dunno why, i guess it was the bit length. The code was provided here https://github.com/leocavalcante/encrypt/blob/master/example/rsa.dart i just changed the text for my name.
On the other hand, the php code was this:

<?php
 $key = file_get_contents('public.pem');
 $string = "joao paulo";
 openssl_public_encrypt($string,$cripted,$key, ***);
var_dump(unpack('C*',$cripted ));
echo  $cripted;

?>

where *** means that i tried every padding avaible.

[leocavalcante]

Hi @zerocoll9

A just created 4 snippets:

encrypt.php

<?php
$key = file_get_contents('public.pem');
openssl_public_encrypt($argv[1], $encrypted, $key);
echo base64_encode($encrypted);
?>

decrypt.php

<?php
$key = file_get_contents('private.pem');
openssl_private_decrypt(base64_decode($argv[1]), $decrypted, $key);
echo $decrypted;

encrypt.dart

import 'dart:io';
import 'package:encrypt/encrypt.dart';

void main(List<String> args) {
  final publicKey = RSAKeyParser().parse(File('public.pem').readAsStringSync());
  final encrypter = Encrypter(RSA(publicKey: publicKey));
  final encrypted = encrypter.encrypt(args[0]);
  print(encrypted.base64);
}

decrypt.dart

import 'dart:io';
import 'package:encrypt/encrypt.dart';

void main(List<String> args) {
  final privKey = RSAKeyParser().parse(File('private.pem').readAsStringSync());
  final encrypted = Encrypted.fromBase64(args[0]);
  final encrypter = Encrypter(RSA(privateKey: privKey));
  final decrypted = encrypter.decrypt(encrypted);
  print(decrypted);
}

And they are fully interoperable:

Terminal

$ dart .\decrypt.dart (php .\encrypt.php "encrypt on php and decrypt on dart")
encrypt on php and decrypt on dart

$ php .\decrypt.php (dart .\encrypt.dart "encrypt on dart and decrypt on php")
encrypt on dart and decrypt on php

---

I think you are missing two points here:

1. Because of padding the resulting binary will never be the same, no matter if is being encrypted on Dart or PHP.
2. The binary representation should be interchangeable, for example I used base64 on the snippets.

[zerocoll9]

Yes, sorry, i just compared they bits and assumed that is a problem. It'll save me, thank you very much.