I’m trying to use the CWLITEARM in order to do the AES loop skip glitch attack. But however, it doesn’t work for any of the glitch_loc ranges from 300 to 340. I’ve tried to tweak the offset and width to no avail, increased the range of the glitch loc to far under and over 300 to no avail, since the key_guess always remains empty. I don’t know what I am doing wrong, since I did change the round variable to be volatile as well. Therefore it should be within the range of 300 to 340 according to the tutorial and other forum threads as well, but for me it doesn’t seem to be working. Could someone help me with it please?

My settings are:

width = 2.75
offset = -12

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I still haven’t found out what’s going wrong, is it just not possible to perform the attack? There are some locations which lets key_guess have a single byte instead of being completely empty, but I doubt that’s the solution since according to the tutorial the full key should be returned. Is there anyone who might be able to help me please?

Are you able to see the target skipping to the last round in the power trace? That’s a much better way to determine if you’re getting the correct glitch.

No, unfortunately the power traces all essentially look the same, in another thread I saw how a glitched power trace looks like and also at what range it would be supposed to occur, unfortunately here it still doesn’t look like this even with these settings. It just looks like the regular power trace (c64’s one)

In that case, I’d recommend probably expanding your ext_offset search a bit, as different compiler versions can move the spot around quite a bit. For reference, I’m pretty sure when I originally
wrote up the tutorial, the correct glitch spot was much earlier (around 170)


For glitch_loc 165 the trace looks like this:


And this is what key_guess contains

(had to make 2 replies because I couldn’t put two images in one reply)

Is this supposed to happen? Because it seems like an incomplete glitch to me since not the whole key is guessed. I found this with ext_offset 31

For which width and offset values did you get this result? I’ve been using width 3 and offset -12 so far. I’m using the ChipWhisperer lite with the ARM target by the way.

Also, my ext_offset is usually the same as the glitch_loc by default, but for ext_offset = 31 I tend to get very consistent power traces like the one I just sent. When looking for other ext_offset values they’re usually the same power trace up until around 100, after which the trace is the same as normal AES execution.