On Fri, Feb 11, 2011 at 4:42 PM, Brian Dunning <brian@xxxxxxxxxxxxxxxx> wrote:
> Hey all -
>
> I'm using mcrypt to store credit cards into MySQL. About 90% of them decrypt fine, but about 10% decrypt as nonsense ("b1ï\ïJEÃUïAïïï" is a good example). Maybe there is a character that appears in about 10% of my encryptions that's not being encoded properly???
>
> // Encryption is set up at the top of the script:
> $crypto = mcrypt_module_open('rijndael-256', '', 'ofb', '');
> $iv = mcrypt_create_iv(mcrypt_enc_get_iv_size($crypto), MCRYPT_DEV_RANDOM);
> $ks = mcrypt_enc_get_key_size($crypto);
> $key = substr(md5('my_funky_term'), 0, $ks);
>
> // When the card number is collected by the form, it's encrypted:
> $cc_number = addslashes($_POST['cc_number']);
> mcrypt_generic_init($crypto, $key, $iv);
> $cc_encrypt = mcrypt_generic($crypto, $cc_number);
> mcrypt_generic_deinit($crypto);
>
> // This is written to the database:
> $query = "update accounts set cc_encrypt='$cc_encrypt', encrypt_iv='$iv', other_fields='$other_stuff' where id='$account_id' limit 1";
> $result = mysql_query($query) or die(mysql_error());
>
> Both the cc_encrypt and encrypt_iv fields are tinytext, latin1_swedish_ci, MyISAM, MySQL 5.0.91
>
> In another script, when I retrieve, I first set it up at the top of the script exactly like step #1 above, then retrieve it like this:
>
> mcrypt_generic_init($crypto, $key, $row['encrypt_iv']);
> $cc_number = trim(mdecrypt_generic($crypto, $row['cc_encrypt']));
> mcrypt_generic_deinit($crypto);
>
> Most of them are good, a few of them are bad. Can anyone see anything I'm doing wrong or a case I'm not covering? Thanks much.
Just a WAG, but when I first was working with mcrypt, it would append
spaces to the encrypted value. I would have to TRIM() everything for
processing or decryption. BTW, we also elected *not* to store card
numbers, only the last 4 digits.
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