C# Rijndael Encrypt and Pel Crypt::CBC

DanielLC

Hi, I'm trying to encrypt a string in c# that would be decrypted with perl. The problem is that in the perl script there is not IV specified so, when I encrypt the result is not readable be the perl decryptor. Is there any workaround to know who perl auto generate the IV (I suppose that's what it does) ?

C# Code to Encrypt :

    private string strCryptoMessage(string strOrig, string strKey)
    {
        System.Security.Cryptography.RijndaelManaged rj = new System.Security.Cryptography.RijndaelManaged();
        rj.Mode = System.Security.Cryptography.CipherMode.CBC;
        rj.Key = Encoding.UTF8.GetBytes(strKey);

        byte\[\] bOrig = Encoding.UTF8.GetBytes(strOrig);

        System.IO.MemoryStream ms = new System.IO.MemoryStream();

        System.Security.Cryptography.CryptoStream cs = new System.Security.Cryptography.CryptoStream(ms, rj.CreateEncryptor(), System.Security.Cryptography.CryptoStreamMode.Write);

        cs.Write(bOrig, 0, bOrig.Length);
        cs.FlushFinalBlock();

        string bResult = Convert.ToBase64String(ms.ToArray());
        ms.Flush();

        
        return bResult;
    }

Perl Code To Encrypt :

#!/opt/local/bin/perl -w

use IO::Socket;
use IO::Handle;
use MIME::Base64;
use Data::Dumper;
use POSIX;
use Getopt::Long;
use strict;

require Crypt::CBC;

my $msg = "MESSAGE_TO_ENCRYPT";
my $enc_key = "SAME_AS_strKey";
my $enc_alg = "Rijndael";

my $cipher = Crypt::CBC->new({
'key' => $enc_key,
'cipher' => $enc_alg,
});

my $encrypted\_msg = $cipher->encrypt($msg);
print "$msg\\n";

my $encoded\_msg = encode\_base64($encrypted\_msg, '');
print "$encoded\_msg\\n";

Both should generate the same result, but I think that the perl Crypt::CBC generate the IV code using the key in some way.