Hi i´ve connected my own target to the Chip Whisperer and removed the Capacitors near the Core Voltage. I also had successful glitch attacks on my own target.
Now i´ve seen that on the delivered target (STM32F303) the Capacitors where not removed. And there is a resistor between the Core Voltage and the Capacitors.
For what are these capacitors (C37/103/104/105/106/108/107) and the resistor (R66) and the inductance L10? Is it to stabilize the Board? Has this no effect on glitch attacks? Should i also add something like that to my setup?
Yup, that’s exactly right. We want a very stable voltage on the high side of the shunt resistor, both for target stability and to help with power analysis. This does affect voltage glitching a bit - if you play around with the shunt resistor value, you should see some different glitch shapes, but the impedance is high enough that the effect isn’t too big.
Edit: Also, this effect isn’t necessarily negative either. In my experience, a bit of ringing on the glitch is a good thing
