code: public function buildSignature(Request $request, Consumer $consumer, Token $token = null)
      {
          $signatureBase = $request->getSignatureBaseString();
  
          $parts = [$consumer->secret, null !== $token ? $token->secret : ""];
  
          $parts = Util::urlencodeRfc3986($parts);
          $key = implode('&', $parts);
  
          return base64_encode(hash_hmac('sha1', $signatureBase, $key, true));
      }
docs: {@inheritDoc}