Re:Hacking a VW Golf Power Steering ECU
by bri3d on Monday January 03, 2022 @10:36AM
(#29781752)
No, this EPS control module is remarkably primitive even by late 2000s standards and several generations behind today's state of the art.
More modern control modules with a bit more resource available to them will use AES as the symmetric encryption (although there are also fixed-key XOR schemes and custom stuff used like this: https://github.com/bri3d/VW_Flash/blob/master/lib/decryptdsg... ).
The keys and even IV are usually fixed across a "model line" of ECUs, so once a decrypted flash memory can be extracted, this isn't much of a protection measure, but it's a lot better than XOR.
Then, in more modern control units, flash areas are also usually protected by both a checksum (usually some CRC permutation, although cute tweaks and random nonsense are common here too) and some form of digital signature.
More modern control modules with a bit more resource available to them will use AES as the symmetric encryption (although there are also fixed-key XOR schemes and custom stuff used like this: https://github.com/bri3d/VW_Flash/blob/master/lib/decryptdsg... ).
The keys and even IV are usually fixed across a "model line" of ECUs, so once a decrypted flash memory can be extracted, this isn't much of a protection measure, but it's a lot better than XOR.
Then, in more modern control units, flash areas are also usually protected by both a checksum (usually some CRC permutation, although cute tweaks and random nonsense are common here too) and some form of digital signature.