bretterer bretterer - 8 months ago 18
PHP Question

cipher class and mcrypt_create_iv is slow at times

I am having an issue with my cipher class. At times it is very fast. Sometimes however it is slow. the code Im using is as follows

class Cipher {
private $securekey, $iv;
function __construct() {
$this->securekey = hash('sha256','51(^8k"12cJ[6&cvo3H/!2s02Uh46vuT4l7sc7a@cZ27Q',TRUE);
$this->iv = mcrypt_create_iv(32);
function encrypt($input) {
return base64_encode(mcrypt_encrypt(MCRYPT_RIJNDAEL_256, $this->securekey, $input, MCRYPT_MODE_ECB));
function decrypt($input) {
return trim(mcrypt_decrypt(MCRYPT_RIJNDAEL_256, $this->securekey, base64_decode($input), MCRYPT_MODE_ECB));
function storeIV() {
return $this->iv;

Are there any suggestions on why this may be slow at times and how I could fix this?


Have you tried the three different second arguments for mcrypt_create_iv(): MCRYPT_RAND (system random number generator), MCRYPT_DEV_RANDOM (read data from /dev/random) and MCRYPT_DEV_URANDOM (read data from /dev/urandom)? Do they offer different consistent speeds? I wonder if it's because /dev/random (the default random source) is running out of collected entropy; the function will block when it does.