Car immobilizers cracked due to crappy proprietary crypto

Karsten Nohl of Security Research Labs, a white-hat hacker, believes that a recent spike in car theft is due to a break in the car immobilizer security systems; thieves are able to re-mobilize the immobilized vehicles. My question is: how long until someone builds a TV-B-Gone for car engines that lets you stop cars with the click of a button?
Juels says that these cracks were possible because the proprietary algorithms that the firms use to encode the cryptographic keys shared between the immobiliser and receiver, and receiver and engine do not match the security offered by openly published versions such as the Advanced Encryption Standard (AES) adopted by the US government to encrypt classified information. Furthermore, in both cases the encryption key was way too short, says Nohl. Most cars still use either a 40 or 48-bit key, but the 128-bit AES - which would take too long to crack for car thieves to bother trying - is now considered by security professionals to be a minimum standard. It is used by only a handful of car-makers...

What's more, one manufacturer was even found to use the vehicle ID number as the supposedly secret key for this internal network. The VIN, a unique serial number used to identify individual vehicles, is usually printed on the car. "It doesn't get any weaker than that," Nohl says.

Criminals find the key to car immobilisers (via Schneier)

(Image: Invalidka - Soviet car for disabled people, a Creative Commons Attribution (2.0) image from dittaeva's photostream)