public static function decode()

in src/JWT.php [85:152]
51 lines of code
20 McCabe index (conditional complexity)

    public static function decode($jwt, $keyOrKeyArray)
    {
        // Validate JWT
        $timestamp = \is_null(static::$timestamp) ? \time() : static::$timestamp;

        if (empty($keyOrKeyArray)) {
            throw new InvalidArgumentException('Key may not be empty');
        }
        $tks = \explode('.', $jwt);
        if (\count($tks) != 3) {
            throw new UnexpectedValueException('Wrong number of segments');
        }
        list($headb64, $bodyb64, $cryptob64) = $tks;
        if (null === ($header = static::jsonDecode(static::urlsafeB64Decode($headb64)))) {
            throw new UnexpectedValueException('Invalid header encoding');
        }
        if (null === $payload = static::jsonDecode(static::urlsafeB64Decode($bodyb64))) {
            throw new UnexpectedValueException('Invalid claims encoding');
        }
        if (false === ($sig = static::urlsafeB64Decode($cryptob64))) {
            throw new UnexpectedValueException('Invalid signature encoding');
        }
        if (empty($header->alg)) {
            throw new UnexpectedValueException('Empty algorithm');
        }
        if (empty(static::$supported_algs[$header->alg])) {
            throw new UnexpectedValueException('Algorithm not supported');
        }

        $key = self::getKey($keyOrKeyArray, empty($header->kid) ? null : $header->kid);

        // Check the algorithm
        if (!self::constantTimeEquals($key->getAlgorithm(), $header->alg)) {
            // See issue #351
            throw new UnexpectedValueException('Incorrect key for this algorithm');
        }
        if ($header->alg === 'ES256' || $header->alg === 'ES384') {
            // OpenSSL expects an ASN.1 DER sequence for ES256/ES384 signatures
            $sig = self::signatureToDER($sig);
        }
        if (!static::verify("$headb64.$bodyb64", $sig, $key->getKeyMaterial(), $header->alg)) {
            throw new SignatureInvalidException('Signature verification failed');
        }

        // Check 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) && $payload->nbf > ($timestamp + static::$leeway)) {
            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) && $payload->iat > ($timestamp + static::$leeway)) {
            throw new BeforeValidException(
                'Cannot handle token prior to ' . \date(DateTime::ISO8601, $payload->iat)
            );
        }

        // Check if this token has expired.
        if (isset($payload->exp) && ($timestamp - static::$leeway) >= $payload->exp) {
            throw new ExpiredException('Expired token');
        }

        return $payload;
    }