Modify the AES Algorith for xmega target

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Hello, i want to try some algorithm countermeasures in the XMega target that comes with the chipwhisperer lite. So i modify the aes.c thats in the tiny-AES128-C directory. For load it into the XMega i do ‘make PLATFORM=CW303 CRYPTO_TARGET=TINYAES128C’ (no idea if this is the way of doing it, probably not because it send me an error). I saw in the tiny-AES128-C directory is another file named aes.h and it is probably the same as aes.c but in hex. Maybe the both files must be the same, and i only modify aes.c.
So my question is: Whats the correct way to modify the aes.c and load it into the XMega target?

Thank you very much in advance! and sorry if my question is too dumb im new in this area.

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Hi Nicolas,

The way you are building this sounds correct - What error are you getting?

Your flow otherwise sounds correct! I think all the stuff you need is in aes.c.

So you’re doing exactly what I would recommend :wink: The error might be in config or where it’s running from etc. Let us know the error message and might make it more obvious what else could be wrong.

-Colin

1 Like
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Thanks for your answer Colin, i was trying to put a delay() for check if the modification works but i forget that i need to include a library hehe. I have two questions more, but they are not from the same topic.
First, a trinstion of a bit from HIGH to LOW or from LOW to HIGH consumes the same amount of energy?
And second, i read in some places that chipwhisperer use synchronous sampling. But im not sure really what that means.
Thank very much in advance!