5 ms·

This line really struck me: "They say you shouldn’t be allowed to modify the code in your car because you might defraud a used car purchaser by changing the mi

This line really struck me: "They say you shouldn’t be allowed to modify the code in your car because you might defraud a used car purchaser by changing the mileage." All you would need to do is checksum to know if the consumer had manipulated the code. Let car owners see the code running on their cars but void liability if the software has been altered.

joezydeco 12y ago
Odometer mileage is data, not code. If I can fake in a new mileage reading and correctly spoof the checksum (without triggering any anti-tamper safeguards), I've committed fraud with no way to trace it back to me.
- cmdrfred 12y ago
  Most of the cars I see anymore have some sort of web connectivity, what if you just send a packet every time you start it? If the mileage suddenly goes from 9000 to 3000 you know you have a problem.
  - joezydeco 12y ago
    There are countless ways you could bypass that and now we're talking about a type of DRM...and DRMs never work. Plus, the idea of a car needing a net connection to operate is a non-starter (excuse the pun).
    - cmdrfred 12y ago
      Not to operate (I'd never purpose such a travesty) but it could work sort of like carfax. Go to buy a used car, Oh it's never been synced with the cloud in its 3 years of existence? I find that rather suspect. Knock off a couple grand.
      - joezydeco 12y ago
        If you pay me $50/year I'll have my server spoof the packet report from your car to the manufacturer's server. It will transmit twice a day at 8:45am and 5:15pm to show the car being driven 5 miles to work and back. Hell, I'll even throw in a lunch outside the office once in a while. Your turn.
        toomuchtodo 12y ago
        Looking forward to your attempt to sidestep crypto. I'll wait while we exhaust the entropy of the universe in a futile attempt to "spoof" a vehicle checking in.
        joezydeco 12y ago
        If I have the car in my driveway, I don't see it being a universe-ending project. We've extracted keys out of way smaller devices.
        poizan42 12y ago
        There's a point here though. Someone somewhere can extract the key out of a single car, but if you have a per-car key and you need to decap a chip and put it under an electron microscope to get the key then it quickly becomes infeasible.
        cmdrfred 12y ago
        There is no perfect system for anything but you can probably take it to the point where an attacker won't profit from his efforts, and I see that as a reasonable goal post for a threat model here. I implement a RSA key for each car, signed before it leaves the factory. Each key is housed in memory that is heavily epoxied and very difficult to remove (in a place that you would have to remove the majority of the engine to reach). The cars ignition system requests validation from the on board key on every start (in fact it gets the actual <start car> command from the chip itself). If the key is not present, the car does not start and instead tells you to return it to the dealership. Now you say, I can remove the key and then reverse engineer it. What if I put n keys? How many do I realistically have to add to make it so time and labor intensive for you to remove my little inexpensive keys that you just give up? Probably not that many. Oh and did I mention that all of them are in an array? Better be sure you didn't miss one or it will zero itself out giving you no hope of recovery. (The warranty specifically mentions this as something that will void it) After all that, if you still want to attempt to modify it. Fine. I'll add 1% to the purchase price of the car and reimburse anyone who bought lemons from your little (illegal) scheme.
  - ptaipale 12y ago
    Around here, we have yearly inspections for cars. (UK would call them MOT tests). The inspector records the mileage every time and it is stored in the motor vehicle register. When buying a used car, you can check on its history (the owner may make the history private so that it's not given to buyers, but then you know that the history is not available and the car might be a lemon). Requires no Web connectivity of my year 2000 Nissan Micra.
- rpedroso 12y ago
  That is a fair point which I had not considered.
sp332 12y ago
You could flash bad firmware that doesn't report mileage correctly, then flash it back before you sell the car.
- yellowapple 12y ago
  That can be at least somewhat deterred by registering the car with the manufacturer to get an unlock code, similar to what HTC does nowadays if you want to root one of its phones. Thus, there's a record of you having installed custom firmware (with the relevant warranty-voiding and such). While it won't specifically detect whether or not mileage reporting has been tampered with, it does signal to a buyer that the software is or was non-stock, and therefore all bets are off, caveat emptor, etc. Alternately, the odometer could (and I'd argue should) be implemented in hardware, possibly as an ASIC (or maybe FPGA) plus dedicated EEPROM to store the counter, wired directly to the relevant sensors. Perhaps some data interface with the main computer, but it should be read-only. That would solve this issue right quick.
higherpurpose 12y ago
Plus, changing the mileage is already quite common (at least in Europe).
logicalmind 12y ago
This is actually easier than you think currently. Most muscle cars (like mustangs/camaros) allow you to change your rear end gearing. Different size rear end gear ratios are different factory options. There are programmers that allow you to tell your computer what gear ratio you running so your speedometer is correct. There are also changes that can be made for bigger/smaller diameter tires. You could change the computer's gear ratio setting and tire size setting. Your speedometer would be way off but you'd also be accumulating fewer miles. It's not directly modifying the mileage of the car, but over time the numbers of miles on the car would be far lower than what they really were. Then once you sell or trade-in the car, just set the settings back to the original ones.
lutorm 12y ago
No worse than the situation was for almost a century of mechanical odometers...
Terr_ 12y ago
We need to separate the technical vs. legal issues here. "Cars should have no anti-tamper mechanisms" != "Owners should be legally able to modify their car." Even changing the mileage is not a crime, the crime occurs if you sell it and commit fraud by lying to the buyer.
- Intermernet 12y ago
  While I agree wholeheartedly with your point, I think some insurance companies, in some countries, may also require an honest readout of the mileage. Once again, not illegal to make the change, but probably fraud if you were to lie to your insurer about it.

joezydeco 12y ago

Odometer mileage is data, not code. If I can fake in a new mileage reading and correctly spoof the checksum (without triggering any anti-tamper safeguards), I've committed fraud with no way to trace it back to me.

cmdrfred 12y ago
Most of the cars I see anymore have some sort of web connectivity, what if you just send a packet every time you start it? If the mileage suddenly goes from 9000 to 3000 you know you have a problem.
- joezydeco 12y ago
  There are countless ways you could bypass that and now we're talking about a type of DRM...and DRMs never work. Plus, the idea of a car needing a net connection to operate is a non-starter (excuse the pun).
  - cmdrfred 12y ago
    Not to operate (I'd never purpose such a travesty) but it could work sort of like carfax. Go to buy a used car, Oh it's never been synced with the cloud in its 3 years of existence? I find that rather suspect. Knock off a couple grand.
    - joezydeco 12y ago
      If you pay me $50/year I'll have my server spoof the packet report from your car to the manufacturer's server. It will transmit twice a day at 8:45am and 5:15pm to show the car being driven 5 miles to work and back. Hell, I'll even throw in a lunch outside the office once in a while. Your turn.
      - toomuchtodo 12y ago
        Looking forward to your attempt to sidestep crypto. I'll wait while we exhaust the entropy of the universe in a futile attempt to "spoof" a vehicle checking in.
        joezydeco 12y ago
        If I have the car in my driveway, I don't see it being a universe-ending project. We've extracted keys out of way smaller devices.
        poizan42 12y ago
        There's a point here though. Someone somewhere can extract the key out of a single car, but if you have a per-car key and you need to decap a chip and put it under an electron microscope to get the key then it quickly becomes infeasible.
      - cmdrfred 12y ago
        There is no perfect system for anything but you can probably take it to the point where an attacker won't profit from his efforts, and I see that as a reasonable goal post for a threat model here. I implement a RSA key for each car, signed before it leaves the factory. Each key is housed in memory that is heavily epoxied and very difficult to remove (in a place that you would have to remove the majority of the engine to reach). The cars ignition system requests validation from the on board key on every start (in fact it gets the actual <start car> command from the chip itself). If the key is not present, the car does not start and instead tells you to return it to the dealership. Now you say, I can remove the key and then reverse engineer it. What if I put n keys? How many do I realistically have to add to make it so time and labor intensive for you to remove my little inexpensive keys that you just give up? Probably not that many. Oh and did I mention that all of them are in an array? Better be sure you didn't miss one or it will zero itself out giving you no hope of recovery. (The warranty specifically mentions this as something that will void it) After all that, if you still want to attempt to modify it. Fine. I'll add 1% to the purchase price of the car and reimburse anyone who bought lemons from your little (illegal) scheme.
- ptaipale 12y ago
  Around here, we have yearly inspections for cars. (UK would call them MOT tests). The inspector records the mileage every time and it is stored in the motor vehicle register. When buying a used car, you can check on its history (the owner may make the history private so that it's not given to buyers, but then you know that the history is not available and the car might be a lemon). Requires no Web connectivity of my year 2000 Nissan Micra.
rpedroso 12y ago
That is a fair point which I had not considered.

sp332 12y ago

You could flash bad firmware that doesn't report mileage correctly, then flash it back before you sell the car.

yellowapple 12y ago
That can be at least somewhat deterred by registering the car with the manufacturer to get an unlock code, similar to what HTC does nowadays if you want to root one of its phones. Thus, there's a record of you having installed custom firmware (with the relevant warranty-voiding and such). While it won't specifically detect whether or not mileage reporting has been tampered with, it does signal to a buyer that the software is or was non-stock, and therefore all bets are off, caveat emptor, etc. Alternately, the odometer could (and I'd argue should) be implemented in hardware, possibly as an ASIC (or maybe FPGA) plus dedicated EEPROM to store the counter, wired directly to the relevant sensors. Perhaps some data interface with the main computer, but it should be read-only. That would solve this issue right quick.

higherpurpose 12y ago

Plus, changing the mileage is already quite common (at least in Europe).

logicalmind 12y ago

This is actually easier than you think currently. Most muscle cars (like mustangs/camaros) allow you to change your rear end gearing. Different size rear end gear ratios are different factory options. There are programmers that allow you to tell your computer what gear ratio you running so your speedometer is correct. There are also changes that can be made for bigger/smaller diameter tires. You could change the computer's gear ratio setting and tire size setting. Your speedometer would be way off but you'd also be accumulating fewer miles. It's not directly modifying the mileage of the car, but over time the numbers of miles on the car would be far lower than what they really were. Then once you sell or trade-in the car, just set the settings back to the original ones.

lutorm 12y ago

No worse than the situation was for almost a century of mechanical odometers...

Terr_ 12y ago

We need to separate the technical vs. legal issues here. "Cars should have no anti-tamper mechanisms" != "Owners should be legally able to modify their car." Even changing the mileage is not a crime, the crime occurs if you sell it and commit fraud by lying to the buyer.

Intermernet 12y ago
While I agree wholeheartedly with your point, I think some insurance companies, in some countries, may also require an honest readout of the mileage. Once again, not illegal to make the change, but probably fraud if you were to lie to your insurer about it.