TimeLimitedToken.php

Go to the documentation of this file.

<?php

namespace SimpleSAML\Auth;

class TimeLimitedToken
{

    protected $secretSalt;

    protected $lifetime;

    protected $skew;

    protected $algo;


    public function __construct($lifetime = 900, $secretSalt = null, $skew = 1, $algo = 'sha1')
    {
        if ($secretSalt === null) {
            $secretSalt = \SimpleSAML\Utils\Config::getSecretSalt();
        }

        if (!in_array($algo, hash_algos(), true)) {
            throw new \InvalidArgumentException('Invalid hash algorithm "'.$algo.'"');
        }

        $this->secretSalt = $secretSalt;
        $this->lifetime = $lifetime;
        $this->skew = $skew;
        $this->algo = $algo;
    }


    public function addVerificationData($data)
    {
        $this->secretSalt .= '|'.$data;
    }


    private function calculateTokenValue($offset, $time = null)
    {
        if ($time === null) {
            $time = time();
        }
        // a secret salt that should be randomly generated for each installation
        return hash(
            $this->algo,
            $offset.':'.floor(($time - $offset) / ($this->lifetime + $this->skew)).':'.$this->secretSalt
        );
    }


    public function generate()
    {
        $time = time();
        $current_offset = ($time - $this->skew) % ($this->lifetime + $this->skew);
        return dechex($current_offset).'-'.$this->calculateTokenValue($current_offset, $time);
    }


    public function generate_token()
    {
        return $this->generate();
    }


    public function validate($token)
    {
        $splittoken = explode('-', $token);
        if (count($splittoken) !== 2) {
            return false;
        }
        $offset = intval(hexdec($splittoken[0]));
        $value = $splittoken[1];
        return ($this->calculateTokenValue($offset) === $value);
    }


    public function validate_token($token)
    {
        return $this->validate($token);
    }
}