What is the role of Android signatures?

1. Application Upgrade: If you want users to seamlessly upgrade to a new version, you must sign with the same certificate. This is because only the same certificate is signed and the system is allowed to install the upgraded application. If you have a different certificate, your application will be asked to take a different package name, in which case it is equivalent to installing a completely new application. If you want to upgrade the application, the signing certificate must be the same, the package name is the same!

2. Application modularity: The Android system can allow multiple applications signed by the same certificate to run in one process, and the system actually takes them as a single application, where we can deploy our application in a modular way, and users can upgrade one of the modules independently.

3. Code or data sharing: Android provides a signature-based permission mechanism, so one application can expose its functionality to another application that is signed with the same certificate. By signing multiple applications with the same certificate and leveraging signature-based permission checks, you can share code and data in a secure way between applications.

What is the role of Android signatures?