[bittercynic]

Though it is possible to set up a GUI to do that, I don't think it is possible to do it in a way that makes it easy to confirm that the app is really doing what it claims to. You may be able to create a system where experts can verify the integrity, but I don't think you can create a computerized system where average people can independently verify the integrity of the system.

Paper, managed by trusted humans, really shines in this kind of task. Maybe some of the trusted humans will turn out to be dishonest, but it is much harder to commit large scale fraud and then cover it up.

[Mononokay]

Open-source the application, and have people check the checksums of the .IPAs and .APKs if they want to verify. A simple GUI wrapper for email wouldn't be particularly complicated implementation-wise, so it wouldn't take a security analyst to vet, either.