What does the equation tell?

Embedded Security Side Channel Power Analysis
1

Hello,
In the “PA_CPA_2-Manual_CPA_Attack” code I don’t quite understand the following equation. Can anyone please help me understand what this equation implies?

image

Thanks!

2

That’s the equation for calculating the correlation between the values we’re testing, in this case sbox(pt ^ key_guess), and a point on our power trace.

PA_CPA_2 is an old tutorial at this point. I’d recommend using courses/sca101 instead.

Alex