Apps random values sent between devices without reverse engineering, possible?

[Terramoto]

Hi,

I'm starting to develop on Android app and i was wondering if there's a way i could use several connected devices to define a random number without the risk of reverse engineering. I dont know much about checking for RE, i thought i could compare md5 checksum from all devices app, but then again that can be RE too, unless there's anything i can do in root?