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So how did examining the hardware allow them to unlock any car? Ideally, shouldn't each car have its own secret key, and no amount of examination of one car or
by ambrop7 13y ago
So how did examining the hardware allow them to unlock any car? Ideally, shouldn't each car have its own secret key, and no amount of examination of one car or its ignition key would reveal the secret key of another one?
The way I interpret this, the manufacturer has thrown a backdoor into the system, allowing access to anyone who knows the backdoor key - and the researchers have managed to extract the backdoor key.
- rtkwe 13y agoFully baking an individualized key into each car is certainly possible, but would require exquisite record keeping and distribution to allow dealers to create new keys to replace lost keys. So instead the individual code is generated based on some information about the car.
- BorgHunter 13y agoWhy not both fully unique and based on information of the car? I could easily imagine a system where [one-way algorithm X] is used to transform the car's VIN into a good cryptographic key, and the dealers then just use some piece of software to program a blank fob with the appropriate key. Done correctly, it would be extraordinarily difficult to reverse engineer.
- rtkwe 13y agoThat's what it sounds like they do just with an added secret. They have some function which maps VINs to key-codes. Just doing that though doesn't prevent someone from uncapping whatever processor is used to do that mapping and then everything is broken. So doing that is still relying on obscurity of the mapping function and isn't any better. Hashes aren't meant to be cryptographically secure, they're meant to protect against corruption.
- mikeash 13y agoI don't think such record keeping qualifies as "exquisite" these days, more like trivial. If Apple can store all relevant info for checking the warranty and unlock status of every iPhone they sell, a car manufacturer can pull it off without too much trouble.