I’ve had an automatic car opener for a decade or so now. Strangely though, I was walking to my car this morning and for the first time I pondered if pressing my button might also open one of the other vehicles in the car park.

I mean, how do these things work? We take them for granted, assume them to be safe and secure, but know nothing about them.

Do they cause brain tumors like mobile phones were once feared to do?

As always when searching for knowledge, I turned to Google and it led me to How Stuff Works. In summary, the keyring device is actually a small radio transmitter. When you push the button it turns on the transmitter and it sends a code to the receiver.

And to answer my question about opening someone else’s door:

Given a 40-bit code, four transmitters and up to 256 levels of look-ahead in the pseudo-random number generator to avoid desynchronization, there is a one-in-a-billion chance of your transmitter opening another car’s doors.

Remarkable!