问题
Do I need to use different certificates to sign different apps if they are all published under the same Google Play account or can I use always the same? If there is no particular requirement, what is the best practice?
回答1:
You don't need to publish all your applications on the same Developper Accout with the same certificate, and can use one certificate per application.
But you must publish updates of an application using the same certificate it has first been published with. This mean that you should make sure that your keystore is saved in severall place.
The best practice is to have a single keystore per developper account, as application using the same certificate can run in the same process, and share data in a secured way (as per the Documentation).
回答2:
No, you don't have to. If you do though, you can declare signature based permissions, so that you can expose services from one of your apps, only accessible to your own apps. The downside is that if you lose the key, you lose all the apps at the same time (you'll have to republish).
回答3:
I prefer having one for each app especially since that makes it easier to transfer an app to somebody else without having to give them the certificate to all your apps.
来源：https://stackoverflow.com/questions/10945353/do-i-need-to-use-the-same-certificate-for-all-my-android-apps