Smart key for two cars

No, at least not with the Gen II Prius. The fobs use a rolling code system that will get out of sync if you use the fob with more than one car. They could be designed to work with more than one car, but so far I know of no one that has made it work.

Tom

 

No.

What you can do is tape the keys together and you have 2 in 1.

 

It's more than just an encrypted RFID, in that the SKS has an active transponder, but functionally you can think of it as such. If you think about it, using the same code each time would be a huge security risk, since anyone with a radio receiver could intercept the code and copy it. Because of this, the encryption or code needs to change with each use. This works by having the fob and car stay together. Each time they successfully negotiate, the fob and car both advance pointers to the next code (effectively if not physically).

If you moved to another car and used the same fob, it would work with that car and then advance to the next code. When you came back to the first car the code would be out of sync.

Obviously this can happen in normal use, so the fob and car have the ability to resync over a limited range. The larger this range, the less security, so there must be a finite limit.

You could design a fob to work with two or more cars, just as the car can work with four fobs. The fob would need to keep track of each car. Technically it isn't hard, but it adds cost.

Most of the security chip manufacturers are pretty tight lipped about how they work, for obvious reasons. One of the most popular is Keeloq from Microchip. You can look at their website for more information:

wwwkeeloqdcPgTitle

Tom