Slashdot Mirror
Monitoring Your Monitor
bje2 writes "Rememeber this story from a couple months ago about reconstructing data from the blinking LEDs of modems...well, CNet is running a story about reconstructing the display of a computer by using special hardware and the reflected glow of the monitor." Kuhn's paper (400k PDF) is available.
Same article appeared on /. back in March, dinnit?
The real danger here, I think, isn't some kind of "national security" or "bank fraud" or anything like that -- security schmecurity. The real danger, is Quake cheating!
Think about it. If I can reconstruct what is on your monitor, I can tell where you are. Are you down the tunnel? In the water? Are you on top of that goddamnfucking sniper tower? I could reconstruct your screen and determine exactly where you are in the Quake map.
Quick, someone, solve this problem before it tears society apart!!
-- Ken Kinder ken@_nospam_kenkinder.com http://kenkinder.com/
Now I can begin selling my high-tech, computer privacy protection devices.
I will call them curtains.
"Until that's resolved, the safest solution is to compute with the lights on. "
Or just close the window shades.
It seems like you can read the contents of a monitor under optimal conditions, but how often do you get optimal conditions? More often that not, a person sits in front of a monitor as he or she works. At best, then, you'd only be able to get bits and pieces of what's on the screen. You also have to contend with different grades of wall paint and/or wallpaper (not to mention furniture behind you) which might make this endeavor fruitless in most cases.
It's a nice trick in a lab, and probably worth publishing. But I think there are too many uncontrollable variables to make this practical.
Now I can justify the 21 LCD at work on the grounds that the CRT poses a risk of industrial espionage.
Nope, no sig
Now you can reconstruct Slashdot from the reflected glow of old stories!
First of all, they're not electrons, they're photons, the quantegy of light. Your CRT has an electron gun that directs a narrow beam of electrons onto a phosphorus coated glass (the 'screen'). The phosphorus then glows, and radiates photons.
While LCD panels don't have an electron beam to radiate phosphorus, they still radiate photons. Otherwise you wouldn't be able to see them.
Basically, if your monitor is radiating photons (read: turned on) someone can intercept those photons and reconstruct an image, given the right equipment and circumstances.
I suppose given the right equipment and circumstances, they can read your mind as well, so we're screwed anyway.
"A terrorist is someone who has a bomb but doesn't have an air force." -William Blum
Imagine a van driving slowly down the streets of a neighborhood every 10 minutes, monitoring the blue TV glow coming out of windows.
Not reconstructing the actual image - just watching the gross flicker patterns, and matching them against all TV stations in real time.
If it finds someone that's not on a known TV station, it pauses for a minute and logs a longer sequence of flickers to match against the flicker patterns of a large library of videos.
Talk about precise marketing info!
Talk about potential blackmail material - ("Did you enjoy your viewing of 'Under-age Girls' last night Mr. Politician? Doing a bit of research, were you?" What about the previous 15 nights?")
Maybe we need to extend "peeping tom" laws to cover any deliberate use of EM radiation coming out of our homes...