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TX · Send📶 300–433 MHz
Vehicle & Garage Remotes (Defence)
Fixed vs rolling codes — and defence
#transmit#keyfob#keeloq#rolling-code#security
What it does
SimpleCars, garages, and gates use little remotes on the sub-GHz bands. This page explains how they work and, importantly, why the modern ones are safe: they use a secret code that changes every single press (a 'rolling code'), so copying one press doesn't help. It's here to teach the security, not to open anyone's car or gate.
How it works
SimpleA fixed-code remote says the same thing every time (easy to copy). A rolling-code remote encrypts a counter that ticks up each press, so every transmission is different and a captured one is useless next time.
How to use it, step by step
Simple- This is for understanding, on your own devices only.
- Learn the difference between fixed and rolling codes.
- See why a changing code defeats copying.
- Understand the defences that keep cars safe.
Examples
Fixed vs rolling
Understand why replaying a rolling-code capture simply doesn't work.
Design a secure remote
Reason through the counter + encryption that makes a remote safe.
Tips & things to try
- The security lesson is the point — modern rolling codes resist replay by design.
- Only ever experiment with your own remotes, and follow local law.