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by farmdve 309 days ago
I am actually fascinated by car electronics. I had heavily modified the software on mine, but it was easier than modern stuff, no encryption of the code, and even the checksum code only triggered a DTC with no consequences.

The only module that was encrypted was the main module, but it if you knew the security PIN you could do what you wanted. It was determined by people that if you observed the jitter of the CAN line fast enough, you could leak the pin via a side channel attack.

But modern car electronics are encrypted, and some probably have security processors that might trigger some irreversible states if you tamper with them. Modern cars are basically as locked up as a PS5.

4 comments

I am fascinated by what you are saying and would love to read more about it. How did you go about modifying the software of some part of your car.

Having worked in this field, I can confirm that most such parts these days come with chip supported read/write protections for part of flash that contain the code. But even with no protections, I think that being able to modify embedded firmware is a feat in itself.

> I had heavily modified the software on mine, but it was easier than modern stuff, no encryption of the code, and even the checksum code only triggered a DTC with no consequences.

What's the vintage of the vehicle? When I was in the 'car enthusiast' phase of my life ECU "reflash/remaps/tunes" were very popular and still happen on more 'modern' cars.

Mazda? Their entire infotainment is just HTML and JavaScript which was quite a shock to discover.
P2 Volvo?
You guessed correctly.
I’ve been following that thread very closely. Prepping myself to install cruise control but as I have a cem-b in my car, I have to solder to the board.

What changes have you made?

For the CEM, I have done no modifications, yet. I have however spent a fair amount of time, reverse engineering the AW55 firmware and have discovered virtually all the maps related to the shifting process, pressures, speeds etc. I have a completely understanding of how the firmware works.

To say I am the only one with such a complete understanding and tuning abilities for it, may not be an understatement.