With IMMOSTOP your phone is what lets your car start, so the link between your phone and the immobiliser is protected at every step — from the chip on the board to the app in your pocket.
Every IMMOSTOP board makes its own random key. No two cars share one, and there is no master key that opens them all.
Each time your phone connects, the board sets a brand-new random challenge that only your phone can answer.
Your phone and board agree their shared key with a modern key exchange (X25519). The key itself is never sent over the air.
Once your phone is paired, the board's button is switched off for good. Nobody can re-pair it at the car.
Lost every phone? A 14-character code gets you back in. It changes after each use and stops accepting attempts after too many wrong ones.
Adding or blocking a tag and registering a new phone all need your password. Not even an installer can add a key without it.
A missing keyring tag can be blocked without touching the car. Your phone updates the car the next time it connects.
Switch on service mode for a service or MOT, set to switch off by itself after a few starts. It never cuts a running engine.
Encrypted memory and secure boot on every board we fit, with the programming port permanently disabled.
Boards only accept firmware signed by IMMOSTOP. Updates arrive over the air through the app.
Your car's key is kept in your phone's hardware-protected key store, the same place banking apps keep theirs.
The app checks it hasn't been modified, and that it's running on a genuine phone, before it will talk to your car.
No. Your phone answers a new random challenge every time it connects, so recording a connection gives a thief nothing they can reuse. The key itself stays inside your phone's secure hardware.
Enter your 14-character recovery code (PUK) in the app on your new phone. The board forgets every old phone and tag, pairs to the new one, and the code changes so it can't be used again.
Yes. Switch on service mode in the app before you drop the car off. You can set it to switch itself off after a few starts so you never forget.
No. Once your phone is paired, the board's button no longer does anything. New phones and tags can only be added from your phone, with your password.
More detail in our article How IMMOSTOP keeps your car's digital key secure.