Automattic / jetpack

			$user_id = (int) $user_id;

			$user = new WP_User( $user_id );

			if ( ! $user || ! $user->exists() ) {

				$this->xmlrpc_verification = new WP_Error( 'unknown_user', sprintf( 'User %d does not exist', $user_id ), compact( 'signature_details' ) );

				return $this->xmlrpc_verification;

			}

		}

		$token = Jetpack_Data::get_access_token( $user_id, $token_key );

		}

		$token = Jetpack_Data::get_access_token( $user_id, $token_key );

		if ( ! $token ) {

			$this->xmlrpc_verification = new WP_Error( 'unknown_token', sprintf( 'Token %s:%s:%d does not exist', $token_key, $version, $user_id ), compact( 'signature_details' ) );

			return $this->xmlrpc_verification;

		}

		$jetpack_signature = new Jetpack_Signature( $token->secret, (int) Jetpack_Options::get_option( 'time_diff' ) );

		if ( isset( $_POST['_jetpack_is_multipart'] ) ) {

		} else if ( is_wp_error( $signature ) ) {

			$this->xmlrpc_verification = $signature;

			return $signature;

		} else if ( ! hash_equals( $signature, $_GET['signature'] ) ) {

			$this->xmlrpc_verification = new WP_Error( 'signature_mismatch', 'Signature mismatch', compact( 'signature_details' ) );

			return $this->xmlrpc_verification;

		}

		$timestamp = (int) $_GET['timestamp'];

		$nonce     = stripslashes( (string) $_GET['nonce'] );