public function authenticate( $user ) {

		// Allow access to the index by default
		if ( '/' === WC()->api->server->path ) {
			return new WP_User( 0 );
		}

		try {

			if ( is_ssl() ) {
				$keys = $this->perform_ssl_authentication();
			} else {
				$keys = $this->perform_oauth_authentication();
			}

			// Check API key-specific permission
			$this->check_api_key_permissions( $keys['permissions'] );

			$user = $this->get_user_by_id( $keys['user_id'] );

			$this->update_api_key_last_access( $keys['key_id'] );

		} catch ( Exception $e ) {
			$user = new WP_Error( 'woocommerce_api_authentication_error', $e->getMessage(), array( 'status' => $e->getCode() ) );
		}

		return $user;
	}