Subversion Repositories cheapmusic

<?php

/**
 *
 * A tiny Nonce generator with variable time-outs.
 *
 * No database required.
 * Each Nonce has its own Salt.
 *
 */
class NonceUtil {

    /**
     * Generate a Nonce.
     *
     * The generated string contains three parts, seperated by a comma.
     * The first part is the individual salt. The seconds part is the
     * time until the nonce is valid. The third part is a hash of the
     * salt, the time, and a secret value.
     *
     * @param $secret required String with at least 10 characters. The
     * same value must be passed to check().
     *
     * @param $timeoutSeconds the time in seconds until the nonce
     * becomes invalid.
     *
     * @return string the generated Nonce.
     *
     */
    public static function generate($secret, $timeoutSeconds = 180) {
        if (is_string($secret) == false || strlen($secret) < 10) {
            throw new InvalidArgumentException("missing valid secret");
        }
        $salt = self::generateSalt();
        $time = time();
        $maxTime = $time + $timeoutSeconds;
        $nonce = $salt . "," . $maxTime . "," . sha1($salt . $secret . $maxTime);
        return $nonce;
    }

    /**
     * Check a previously generated Nonce.
     *
     * @param $secret the secret string passed to generate().
     *
     * @returns bool whether the Nonce is valid.
     */
    public static function check($secret, $nonce) {
        if (is_string($nonce) == false) {
            return false;
        }
        $a = explode(',', $nonce);
        if (count($a) != 3) {
            return false;
        }
        $salt = $a[0];
        $maxTime = intval($a[1]);
        $hash = $a[2];
        $back = sha1($salt . $secret . $maxTime);
        if ($back != $hash) {
            return false;
        }
        if (time() > $maxTime) {
            return false;
        }
        return true;
    }

    private static function generateSalt() {
        $length = 10;
        $chars = '1234567890qwertyuiopasdfghjklzxcvbnmQWERTYUIOPASDFGHJKLZXCVBNM';
        $ll = strlen($chars) - 1;
        $o = '';
        while (strlen($o) < $length) {
            $o .= $chars[rand(0, $ll) ];
        }
        return $o;
    }

}

?>