Re: AES_ENCRYPT() in php

[Rolf Martin-Hoster]

This was driving me up the wall. Here ya go :

$val='data to encrypt';
$ky='asdf';

$mode=MCRYPT_MODE_ECB;
$enc=MCRYPT_RIJNDAEL_128;
$numblock=floor(strlen($val) / 16);
$pad_len= 16-(strlen($val) % 16);
$val=str_pad($val, (16*(floor(strlen($val) / 16)+1)), chr($pad_len));
$encrypted_val=mcrypt_encrypt($enc, $ky, $val, $mode, mcrypt_create_iv( mcrypt_get_iv_size($enc, $mode), MCRYPT_DEV_URANDOM));



Please note that the key ($ky) has to be 16 characters or less. MYSQL splits keys longer than 16 into blocks of 16 and then XORS the value. There is a bug (which I have duplicated in the code to prevent problems with mysql's bug) in that if the length of the $val % 16 == 0 an extra padded block is added to value to be encrypted and the value that is added it the length of th block (or length to be padded for $val % 16 != 0)



Edited 1 time(s). Last edit at 03/10/2006 01:22PM by Rolf Martin-Hoster.