Using H-field probe for CPA on Firmware Implementation of AES

1

Hello,

We are using an H-field probe for the CPA attack on firmware implementation of AES lab. We have completed the lab without the probe and are now attempting to use it. However, when using the probe, the plot of the captured traces appears incorrect, similar to when the Target Board and the ChipWhisperer are not connected. We watched the H-field probe YouTube tutorial with the older software, increased the number of captured traces and changed the diameter of the probe, but the issue persists.

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2

Have you tried increasing the gain?

3

Thanks for your response.

When we increase the gain to the maximum, we at least get a plot that looks like this:

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However, the key guess in the next step is incorrect:
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Could this be due to the inaccuracy of using the H-field probe? If so, how can the H-field probe be used effectively for a lab like this?

4

Experiment with probe placement; and you’ll likely need more traces (compared to shunt measurements) to account for the reduced SNR.