Wednesday, September 1, 2010

Using Car Remote Entry Key Fobs For Payments?

There is a news story that suggests people will be using the remote keyless entry systems for their cars as payment systems.  (So now your car key transmitter might have "lock", "unlock", and "pay" buttons.)  Do you think this is a good idea?

I did some design work on a previous generation of this technology. Cryptographic algorithms I developed jointly with Alan Finn were in a lot of model year 1994-2004 cars. What struck me about this market was the extreme cost sensitivity of things. No way could we afford industrial strength crypto.  The competition all had laughable crypto or made what I consider rookie mistakes (for example, using the same manufacturer key in all devices).  I never heard that my algorithm was broken during its designed 10-year life (but I'll bet the NSA had a nice chuckle when they saw it).  But other algorithms have proved to be insecure. For example, the Keeloq system has become the target of numerous attacks.  While the first published attacks are relatively recent, people likely knew about the weaknesses and could have attacked them a lot earlier if they had wanted to do so. While technology has changed over the years, these important lessons probably are the same:
  • You have to have real security experts work on these products. You can't just put something together without really knowing your stuff or you will make rookie mistakes.
  • You have to have some appreciation for security by the customers buying the systems (often it is a car manufacturer deciding how good is good enough). Too often decisions are made on "cheap and not obviously bad" rather than "is actually secure." One of the best things that happened to me in my experience was that the customer had someone (his name is Tom) who understood crypto and was willing to back us when I said we couldn't go below a certain cost threshold without compromising security beyond the required level.
  • You have to use real crypto now, not cheesy crypto. Attackers have gained in sophistication and if someone has time to attack an old Keeloq system they'll attack your system.
  • Once you let a key fob control money, it's a lot more attractive to attack. So it is sure to be attacked.
  • Cars have a 10-15 year life, multi-year production runs, and easily a 3-5 year lead time. So you have to plan for your approach to be secure 20-25 years from now. That's hard to do in any system, much less one that is supposed to be inexpensive.
I predict next generation devices will have vulnerabilities due to failure to appreciate the above bullets. It has happened in the past, and it will happen in the future. I don't plan to use my key fob transmitter to make payments any time soon, and I used to design these things for a living. But then again, as long as you read about problems in the news before you're the victim of an attack, maybe you'll be OK.

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