Re: Help! Made a boo-boo encrypting credit cards

On Fri, Feb 11, 2011 at 4:42 PM, Brian Dunning <brian@briandunning.com> 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 ("b1�\�JEÚU�A���" 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.