RSA (K-ary) on XMEGA target

Hi, I’m trying to capture some RSA traces, but with a K-ary exponentiation method. I took the tutorial “PA_SPA_2-RSA_on_XMEGA_8bit” as starting point and got to capture some traces, however I got an error when building:


As can be seen in the figures, there is an error when compiling, but the the target is then programmed succesfully. My first questions are: are the obtained traces the right ones? How do I solve the errors shown in the first figure with the undeclared commands “simpleserial_addcmd(‘1’, 0, sig_chunk_1);” and “simpleserial_addcmd(‘2’, 0, sig_chunk_2);”?

As a next step, once the previous aspect is solved, I will need to modify the exponentiation method of the RSA. From what I undertood, I need to modify the C file “[/hardware/victims/firmware/crypto/avrcryptolib/bigint/bigint.c]”, which is called by " [hardware/victims/firmware/crypto/avrcryptolib/rsa/rsa_basic.c]"
Could anyone confirm me if I am right?

Any help is wellcome, thanks!:slight_smile:


You can just comment out those simpleserial_add commands for now, as they’re only used for RSA on the Arm targets. We’ll get that fixed up for the 5.6.0 release. You’re probably programming some old firmware right now.

Yup, bigint.c does the modular exponentiation in avrcryptolib.


Thanks for the answer Alex!