Modifying the booloader

Greetings everyone,

I’m trying to build a scenario on breaking AES (straight). The catch is that the key is hardcoded into the bootloader (instead of getting it from the chipwhisperer software).

Has anyone worked on such kind of changes. I tried overwriting and ignoring the key in the bootloader… didn’t work. Maybe my C skills are a little rusty :frowning:

Any help would be much appreciated.

Sure, you can definitely do this. It doesn’t matter if the fixed key is a secret stored in the bootloader or a constant that we send over UART for every encryption - side channel analysis doesn’t know the difference.

The only catch is that, if the key is a secret, the ChipWhisperer Analyzer can’t tell if its answer is correct. You can turn off key highlighting in Results > Attack Settings > Highlighted key - set this to None and the analyzer will stop showing you the wrong answer.