Reverse Engineering Access Control Fobs on the Cheap: No Encoder Hardware Required

The Problem
A while back, I was tasked with a project, which I delegated to my staff, in which we migrated from simplex mechanical pushbutton locks to a modern key fob access control system. The system (which I’ll leave nameless for some anonymity) came with pre-configured fobs at a per-unit cost. This was circa 2023, and at the time the Flipper Zero was getting a lot of press.



It’s 2025. And let’s be real — online privacy is still treated more like an upsell than a right. I started caring about digital privacy back in 2014 when I realized just how much metadata could say about you, even when your actual content was encrypted.