PHP implementation of SSO with JWT

gistfile1.php

<?php

// load JWT class
// Class can be found here: https://github.com/firebase/php-jwt
include __DIR__.'/JWT.class.php';
$JWT =  new JWT();


// Zendesk provides a timestamp in the get.
$now = (!empty($_GET['timestamp'])) ? $_GET['timestamp'] : time();


// Information array send to zendesk. For all available options see: https://support.zendesk.com/entries/23675367 under: "Table 1. Supported attributes"
// {username} and {email@address} are username/email address of the user you are trying to login.
$payload = array(
    "jti" => md5($now . rand()),
    "iat" => $now,
    "name" => '{username}',
    "email" => '{email@address}'
    );


// The zendesk SSO token is generated @ zendesk.com under settings/security/end-user
$jwtZD = $JWT->encode($payload, '{zendesk SSO token}');


// Domain is the zendesk domain
header('Location: https://{domain}.zendesk.com/access/jwt?jwt=' . $jwtZD . '&return_to=' . $_GET['return_to']);