Hi all,
Since this thread is a bit scattered and the process for .apk signing has changed since it was started, I created an Unreal Wiki page that goes step by step through the most current process (as of Unreal 4.12). Link here:
These instructions are based on my own experience struggling to correctly sign an .apk app for distribution recently. If you find any errors or omissions in this walkthrough, please let me know and I’ll do my best to correct it ASAP.