/** * Generates a psuedo-random string of the specified length. * * @param integer $length * * @return string */ public static function generateRandomString($length) { while (strlen(self::$_randomData) < $length) { // openssl_random_pseudo_bytes is *ridiculously* slow on windows if (function_exists('openssl_random_pseudo_bytes') && substr(PHP_OS, 0, 3) != 'WIN') { self::$_randomData .= bin2hex(openssl_random_pseudo_bytes(max($length, 1024) / 2)); } else { self::$_randomData .= md5(uniqid(mt_rand(), true)); } } $return = substr(self::$_randomData, 0, $length); self::$_randomData = substr(self::$_randomData, $length); return $return; }
/** * Generates a psuedo-random string of the specified length. * * @param integer $length * @param boolean $raw If true, raw binary is returned, otherwise modified base64 * * @return string */ public static function generateRandomString($length, $raw = false) { $mixInternal = false; while (strlen(self::$_randomData) < $length) { if (function_exists('openssl_random_pseudo_bytes') && (substr(PHP_OS, 0, 3) != 'WIN' || version_compare(phpversion(), '5.3.4', '>='))) { self::$_randomData .= openssl_random_pseudo_bytes($length); $mixInternal = true; } else { if (function_exists('mcrypt_create_iv') && version_compare(phpversion(), '5.3.0', '>=')) { self::$_randomData .= mcrypt_create_iv($length, MCRYPT_DEV_URANDOM); $mixInternal = true; } else { if (substr(PHP_OS, 0, 3) != 'WIN' && @file_exists('/dev/urandom') && @is_readable('/dev/urandom') && ($fp = @fopen('/dev/urandom', 'r'))) { if (function_exists('stream_set_read_buffer')) { stream_set_read_buffer($fp, 0); } self::$_randomData .= fread($fp, $length); fclose($fp); $mixInternal = true; } else { self::$_randomData .= self::generateInternalRandomValue(); } } } } $return = substr(self::$_randomData, 0, $length); self::$_randomData = substr(self::$_randomData, $length); // have seen situations where duplicates may be read(!?!) so mix // in another source if ($mixInternal) { $final = ''; foreach (str_split($return, 16) as $i => $part) { $internal = uniqid(mt_rand()); if ($i % 2 == 0) { $final .= md5($part . $internal, true); } else { $final .= md5($internal . $part, true); } } $return = substr($final, 0, $length); } if ($raw) { return $return; } // modified base64 to be more URL safe (roughly in rfc4648) return substr(strtr(base64_encode($return), array('=' => '', "\r" => '', "\n" => '', '+' => '-', '/' => '_')), 0, $length); }