in reply to decrypt problems with Crypt::Rijndael (datasize not multiple of blocksize)

Thanks for the replies. I guess this is more of a general question because my encryption/decryption scripts work (they encrypt the data and I'm able to decrypt until this one). But here is the code doing the work: 
ENCRYPT SCRIPT
#!/usr/bin/perl
use DBI;
use Crypt::Rijndael;

$iv = 'same_16_character_string';
$cipher = Crypt::Rijndael->new( "a" x 32, Crypt::Rijndael::MODE_CBC );
$cipher->set_iv($iv);

$data = $cipher->encrypt($some_data);

** $data is then inserted into a blob field in mysql (data in the acco
+unts table)


DECRYPT SCRIPT
#!/usr/bin/perl
use DBI;
use Crypt::Rijndael;

$iv = 'same_16_character_string';
$cipher = Crypt::Rijndael->new( "a" x 32, Crypt::Rijndael::MODE_CBC );
$cipher->set_iv($iv);

$sql_data = "SELECT data FROM accounts WHERE account_id = '237' LIMIT 
+1";
$qry_data = $dbh->prepare($sql_data);
$qry_data->execute();
$data = $qry_data->fetchrow_hashref();
$data = $data->{data};
print $cipher->decrypt($data) . "\n\n";

[download]
So as you can see I do no extra work on the data before it is inserted into the blob field...just a simple encrypt. The problem now is I have a piece of data encrypted this way that won't decrypt. I get that error on the $cipher->decrypt($data) line, but only with this specific piece of data.
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Re^2: decrypt problems with Crypt::Rijndael (datasize not multiple of blocksize)
by ikegami (Patriarch) on Sep 29, 2008 at 19:12 UTC

    Notice the first line of the documentation?

    "Crypt::CBC compliant Rijndael encryption module"

    That should tell you something! 

    use Crypt::CBC;
my $key = "a" x 32;
my $cipher = Crypt::CBC->new( -cipher => 'Rijndael', -key => $key );
my $ciphertext = $cipher->encrypt($plaintext);

    [download]
    use Crypt::CBC;
my $key = "a" x 32;
my $cipher = Crypt::CBC->new( -cipher => 'Rijndael', -key => $key );
my $plaintext  = $cipher->decrypt($ciphertext);

    [download]

    It handles padding, for you.
    It handles salting for you.
    It handles chaining for you.

    And make sure your database field is large enough.

[reply]
[d/l]
[select]
Re^2: decrypt problems with Crypt::Rijndael (datasize not multiple of blocksize)
by Illuminatus (Curate) on Sep 28, 2008 at 19:16 UTC
    So close, and yet so far... You have left out the critical (and most likely problematic) piece; the DB insertion. I will bet that if you try to decrypt immediately after you encrypt, it will work fine. The problem is that either your insert or select is munging up the data. I have not used blobs with perl/dbi, so I am not aware of specific issues. Look at http://www.james.rcpt.to/programs/mysql/blob/. Is this the way you are creating the insert?
[reply]
      I can't imagine that's the problem, but I guess it's possible. Here's the update: 
      $sql_update = "UPDATE accounts SET data = '" . $data . "', encrypted =
+ '1' WHERE account_id = '" . $account_id . "'";
$qry_update = $dbh->prepare($sql_update);
$qry_update->execute();

      [download]
      $data is the encrypted piece
[reply]
[d/l]

        Use placeholders! 

        $sql_update = 'UPDATE accounts SET data = ?, encrypted = 1 WHERE accou
+nt_id = ?';
$qry_update = $dbh->prepare($sql_update);
$qry_update->execute($data, $account_id);

        [download]
[reply]
[d/l]

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