> One interesting difference and trend in automotive control modules (also mentioned in Willem's fantastic write-up) is that many EU modules started adding signature checking and encrypted updates in the late 2000s
Do you mean the XOR encryption used? As someone working on the embedded linux(!= than embedded MCU) side i was very surprised to find such a crude "encryption" scheme employed. On the other hand i reckon there is only so much encryption an 8bit MCU can do. Also tolerance for complex encryption designs must be very low when you are trying to limit the scope of a life critical component.
The anti brute force measure was a bit more refined and almost got the job done.
Regardless, i agree. An great write-up. The binwalk and narrow down of possible CPUs used due to the ASIL-D constraint were really illuminating.
Do you mean the XOR encryption used? As someone working on the embedded linux(!= than embedded MCU) side i was very surprised to find such a crude "encryption" scheme employed. On the other hand i reckon there is only so much encryption an 8bit MCU can do. Also tolerance for complex encryption designs must be very low when you are trying to limit the scope of a life critical component.
The anti brute force measure was a bit more refined and almost got the job done.
Regardless, i agree. An great write-up. The binwalk and narrow down of possible CPUs used due to the ASIL-D constraint were really illuminating.