> Q: What is the best way to prevent the two demonstrated attacks?

> A: Use the most updated cryptographic libraries available.

Or what about covering the LED(s) with something so that the camera filming the top secret computer non-stop doesn't have a chance to exploit the side channel?

(excuse the sarcasm; but they were such low-hanging fruits I couldn't resist. The awareness is indeed important, as there are countless other side channels such as USB-cabled mice and keyboards with LEDs...

Also: I'm writing this from a hotel room with a TV illuminating the darkness with its bright standby blue melatonin killer LED - about to hang a towel over it)