RandHash

gistfile1.aw

<?php
/**
* A class for true random hash string generation.
*/
class RandHash
{
    /**
    * @param string $prefix to be used with uniqid()
    * @return string hash
    */
    public static function get($prefix='abc') {
        $bytes = '';
         
        if (function_exists('openssl_random_pseudo_bytes')
        && (strtoupper(substr(PHP_OS, 0, 3)) !== 'WIN')) // OpenSSL slow on Win
        $bytes = openssl_random_pseudo_bytes(32);
         
        if ($bytes === '' && is_readable('/dev/urandom')
        && ($hRand = @fopen('/dev/urandom', 'rb')) !== FALSE) {
        $bytes = fread($hRand, 32);
        fclose($hRand);
        }
         
        if ($bytes === '') {
        $key = uniqid($prefix, true);
         
        // 12 rounds of HMAC must be reproduced / created verbatim, no known shortcuts.
        // Salsa20 returns more than enough bytes.
            for ($i = 0; $i < 12; $i++) {
            $bytes = hash_hmac('salsa20', microtime() . $bytes, $key, true);
            usleep(10);
            }
        }
        return base64_encode($bytes);
    }
}