Hector Martin

Reminder: the CovertChannels stuff from Mordechai Guri is a paper mill with misleading titles. Stop giving them publicity. They aren't "Generating Covert Wi-Fi signals", they're encoding 10bps of data in 2.4GHz noise from a 2.4GHz RAM bus. That's not Wi-Fi.

Literally the guy's entire schtick is picking a random noise/EMI output from a computer (he's done fan noise, HDD LEDs, temperature, etc), figuring out how to write software to encode data in the noise the least-effort amount of way, then pumping out a paper.

Anyone can come up with this stuff and implement it. Seriously. Like half of the papers only take a few lines of code to implement on both the transmitting and receiving sides (you need malware on both sides).

I was going to give you some ideas, but he's already done most of them (I looked around, thought "screen brightness" - yup, he did it last year). Uhh, let's see... camera LED! He's done keyboard LEDs, HDD LEDs, router LEDs, but not camera LEDs! Hey Morderai, free paper!

Here's your leaking code: xxd -c 1 -p secret.txt | while read a; do for b in ${a:0:1} ${a:1:1}; do ffmpeg -y -f v4l2 -i /dev/video0 -t $((0x$b)) -f rawvideo /dev/null ; done; done 4 bits per pulse PWM encoding. Tested on my iMac. There's half of your paper! You're welcome!

One idiotic idea I came up with a while back is to spin up a GPU load as a form of on-off keying, and use an SDR to grab the unencrypted signals from a wireless energy monitor to exfiltrate maybe 8 bits per minute.