The meaning and usage of Android signature

One: The meaning of the signature:
With so many people developing Android, it's entirely possible that we all put the class name, the package name, in the same name, how do you differentiate it? Signature is a distinguishing function.
Since the developer may be confused by using the same package name to replace the installed program, the signature can guarantee a considerable name, but the signature of different packages is not replaced.
APK If you use a key signature, a file signed by another key when it is published will not install or overwrite the old version, preventing your installed app from being overwritten or replaced by a malicious third party.

This signature is actually a developer's identity. When something happens in a transaction, a signature can prevent it from happening.

Second: Eclipse default signature

All Android apps must have digital signatures, no applications that do not have digital signatures, including those running on the emulator. Android does not install apps without a digital certificate.
Signed digital certificates do not require authority to authenticate, is the developer's own production of digital certificates, known as self-signed.
Simulator development environment, the development of the program through the ADB interface upload will be automatically signed with the debug permission before passing to the emulator.
As shown in the Eclipse menu, Windows-Preferences-android–> Build shows our default signing digital certificate for debugging.

Three: Use Eclipse to export a custom signature apk

1. Right-click Project in Eclipse Project, select Android tool in the popup option → Generate signature app package:

2. Select the Android project that needs to be packaged:

3, if there is a private key file, select the private key file to enter the password, if there is no private key file see steps 6th and 7 to create a private key file:

4. Enter the private key alias and password:

5. Select the location of the APK package storage and complete the setup to start generating the APK signature package:

6. If you do not have a private key file, create a private key file:

7. Enter the required information for the private key file and create:

The meaning and usage of Android signature