public static function decode($jwt, $key = null, $allowedAlgs = array(), $extraSeconds = 0)
{
$tks = explode('.', $jwt);
if (count($tks) != 3) {
throw new \UnexpectedValueException('Wrong number of segments');
}
list($headb64, $bodyb64, $cryptob64) = $tks;
if (null === ($header = json_decode(JWT::urlsafeB64Decode($headb64)))) {
throw new \UnexpectedValueException('Invalid header encoding');
}
if (null === ($payload = json_decode(JWT::urlsafeB64Decode($bodyb64)))) {
throw new \UnexpectedValueException('Invalid claims encoding');
}
$sig = JWT::urlsafeB64Decode($cryptob64);
if (isset($key)) {
if (empty($header->alg)) {
throw new \DomainException('Empty algorithm');
}
if (empty(self::$supportedAlgs[$header->alg])) {
throw new \DomainException('Algorithm not supported');
}
if (!is_array($allowedAlgs) || !in_array($header->alg, $allowedAlgs)) {
throw new \DomainException('Algorithm not allowed');
}
if (is_array($key)) {
if (isset($header->kid)) {
$key = $key[$header->kid];
} else {
throw new \DomainException('"kid" empty, unable to lookup correct key');
}
}
if (!JWT::verify("{$headb64}.{$bodyb64}", $sig, $key, $header->alg)) {
throw new SignatureInvalidException('Signature verification failed');
}
// Check if the nbf if it is defined. This is the time that the
// token can actually be used. If it's not yet that time, abort.
if (isset($payload->nbf) && $payload->nbf > time()) {
throw new BeforeValidException('Cannot handle token prior to ' . date(\DateTime::ISO8601, $payload->nbf));
}
// Check that this token has been created before 'now'. This prevents
// using tokens that have been created for later use (and haven't
// correctly used the nbf claim).
if (isset($payload->iat) && $payload->iat > time()) {
throw new BeforeValidException('Cannot handle token prior to ' . date(\DateTime::ISO8601, $payload->iat));
}
// Check if this token has expired.
if (isset($payload->exp) && time() >= $payload->exp + $extraSeconds) {
throw new ExpiredException('Expired token');
}
}
return $payload;
}
