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Comment by DoctorOetker | Hacker News Reader

the oscilloscope has 20 MHz bandwith, any old VGA monitor (CRT/LCD/etc) has at least 3 30MHz ADCs (1024x768x60=~60Msps=~30MHz bandwidth).

ADC's may be expensive in low volume discrete form, but integrated in (standardized!) peripheral bus (USB) controllers, this could be very cheap.

As always, it depends on the threat model: do you wish to protect against manufacturers/nation states or not?

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I would love to read a more thorough explanation of what you're suggesting.

I believe they are suggesting that the above comment "Short of a oscilloscope hiding in the computer you use" might not be so far fetched. The hardware needed to do the type of analysis used for this attack has been around a long time and is presumably very cheap at scale. So if for example a nation/company that has control over the manufacture of a large number of USB controllers decided they wanted to be able to do this kind of power analysis on all USB devices plugged into their controllers they could do so easily.

Esentially adding a micro controller with an Analog to Digital converter that can watch the power pin inside the USB controller/port itself would be relatively simple and cheap.

Although they don’t have 20MHz of bandwidth and the necessary sample rate there are USB3 power delivery controllers on the market today which do exactly that. Some even embed the microcontroller too.

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