Help needed with timeout in combination with glitching

Embedded Security ChipWhisperer Software
1

Dear all,

Setup: CWLITEARM
SW version: 5.1.3

I need some help with the following problem.
We want to attack a cryptographic algorithm that requires a very loooong runtime. All attempts (and there were really many) did not lead to success. Is it possible to influence the timeout between trigger_high() and trigger_low()?
With the parameter “scope.adc.timeout” a capture only waits for a trigger_high(), but since we want to glitch randomly in the range between trigger_high() and trigger_low(), the capture should wait for the trigger_low(). Also, attempts with several captures, unfortunately, did not lead to the desired result.

Are we possibly following the wrong approach?

Many thanks in advance!

Cheers,
Fabio

2

Hi Fabio,

I don’t think there’s any sort of timeout on glitching. I at least didn’t run into anything like that when I wrote the RSA tutorial (https://chipwhisperer.readthedocs.io/en/latest/tutorials/fault_5-openadc-cwlitearm.html#tutorial-fault-5-openadc-cwlitearm), glitching at an offset of 7 million cycles.

If you want to glitch randomly between trigger_high() and trigger_low(), you’re probably best off finding the trigger length ( scope.adc.trig_count, clocked off of the ADC clock, so you may want to change it to clkgen_x1 to keep it on the same sample scale as the glitch module) and using a random function within those bounds.

Alex