我相信您只有在侧加载应用程序时才需要对其进行签名。如果您将其上传到Windows应用商店，则Microsoft将为您签名该应用。

I believe you only need to sign your app if you are sideloading it. If you upload it to the Windows Store, Microsoft will sign the app for you.

来自MSDN文章提交Windows 8应用：

签名和发布。在最后一步，我们将使用与开发者帐户的技术细节匹配的受信任证书对您提交的软件包进行签名。这样可以向客户保证该应用程序已通过Windows应用商店的认证，并且未被篡改。

Signing and publishing. In this final step, we'll sign the packages you submitted with a trusted certificate that matches the technical details of your developer account. This provides customers with the assurance that the app is certified by the Windows Store and hasn't been tampered with.