January 28, 2018 Written by

The ChipWhisperer-Lite is a good platform to learn the basics of side channel attack. As we go further we need more power to break more applications and hardware. Our institute has a Rhode & Schwarz RTO 1022 digital oscilloscope with 2 GHz and 10GSa/s.

Special thanks to Prof. Dr. Kruse who gave us the chance to use this device for our purpose. This digital oscilloscope (DSO) offers better performance than the ChipWhisperer and the option to save the data on an USB flash drive to calculate on a PC.

Illustration 1: Measure setup with Oszilloskop

Illustration 2: Measure setup

In the illustrations 1 and 2 you can see how the ChipWhisperer-Lite is connected to the target board and the oscilloscope. In the schedule of the target board we have discovered that the glitch and the measure SMA connectors are internally connected, so we used the glitch output for the oscilloscope. In the illustration you can also see that the breaking AES measurement was performed with 50 traces. The 50 traces are the 50 peaks you can see on the oscilloscope.

The script used in tutorial B6 need just a little tuning to run with the data the DSO gave us. To read the data from the csv file, we use a numpy function called getfromtxt and set the delimiter on line breaks. Because the ChipWhisperer software handles each trace separately, we reshape the data from the digital oscilloscope in 50 shunks. The first and the last part where no peaks are were cut away and the 50 peaks were put in 50 single parts for the calculation.

Illustration 3: Script modification

Once this is implemented, the rest of the script stays the same, because the data can now be handled by the correlation.