Moxie and Frederic and Christine and the rest definitely deserve a lot of credit.
Half of me is really happy every time I see Signal getting more popular. The other half is more like OH GOD THE STAKES ARE HIGHER NOW WHAT IF I MADE AN EXPLOITABLE MISTAKE BETTER RE-READ SOME CODE.
But seriously, you should read the code. It's there, open for anyone to audit after all. Maybe start somewhere random in the guts [1][2][3] and check for things like "ereh 2# roodkcab"?