/**
* @param object|array $payload PHP object or array
* @param string $key The secret key
* @param string $kid The key id
* @param string $algorithm The signing algorithm
*
* @return string A JWT
*/
public static function encode($payload, $key, $kid = null, $algorithm = 'HS256')
{
$header = array('typ' => 'JWT', 'alg' => $algorithm, 'kid' => $kid);
$segments = array();
$segments[] = JWT::urlsafeB64Encode(JWT::jsonEncode($header));
$segments[] = JWT::urlsafeB64Encode(JWT::jsonEncode($payload));
$signingInput = implode('.', $segments);
$signature = JWT::sign($signingInput, $key, $algorithm);
$segments[] = JWT::urlsafeB64Encode($signature);
return implode('.', $segments);
}