My boyfriend’s apartment recently upgraded from metal keys to key fobs and I recently moved offices, retiring the old code for pressing my student card against a reader.  It got me thinking, how exactly do these devices work?  What is their security like?  Unfortunately, the internet understands “fob” as something completely different, however, I did find some interesting information regarding remote entries, such as to your car.

How remote entry works:  http://auto.howstuffworks.com/remote-entry2.htm
Reprogramming a remote (including how to use one remote for two cars): http://hackaday.com/2010/07/13/key-fob-programming/