Radiation emitted by wired keyboard

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SUMMARY

The discussion centers on the electromagnetic radiation emitted by wired keyboards when keys are pressed, with a focus on building a keylogger based on this phenomenon. Participants note that while all keys emit similar low-frequency radio noise, distinguishing between individual key presses is challenging. Suggestions include using a sensitive RF antenna to detect variations in the electromagnetic emissions, which are influenced by the keyboard's scanning mechanism. Historical context is provided, referencing past concerns about electromagnetic emissions from CRT displays.

PREREQUISITES
  • Understanding of electromagnetic radiation principles
  • Familiarity with RF antennas and their applications
  • Knowledge of keyboard scanning mechanisms
  • Basic electronics and signal processing skills
NEXT STEPS
  • Research the types of RF antennas suitable for detecting low-frequency emissions
  • Study keyboard scanning techniques and their impact on electromagnetic emissions
  • Explore historical cases of electromagnetic eavesdropping, particularly with CRT displays
  • Investigate legal and ethical implications of keylogging and electromagnetic surveillance
USEFUL FOR

Electronics students, hobbyists interested in signal processing, cybersecurity professionals, and anyone exploring the intersection of hardware and electromagnetic theory.

YanivW
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Hi,
I heard before that wired keyboards emits radiation when a key is clicked. My goal is to build a keylogger based on this phenomenon (for fun, of course). I've already seen some variations of this idea, but they were all using wireless keyboard, where it is much more simple to detect and process the RF radiation.
I want to learn more about this, but can't find anything on the internet (the spectrum of the emitted radiation for example). I'll be glad if someone could help me find more information that can be relevant, or share from his own knowledge.
Thanks!
 
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You'll need to give a link to this supposed phenomenum.
However any electrical switch will emit a tiny amount of EM radiation when the contact is closed.
Mainly 'white noise' at the very low end of the spectrum (aka radio).
In the case of a keyboard I doubt there is a way to determine which particular key was pressed,
All of them would emit a similar radio 'click'
 
:wink:Too bad you can't send your question to the NSA. If it can be done, they probably did it.
 
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rootone said:
You'll need to give a link to this supposed phenomenum.
However any electrical switch will emit a tiny amount of EM radiation when the contact is closed.
Mainly 'white noise' at the very low end of the spectrum (aka radio).
In the case of a keyboard I doubt there is a way to determine which particular key was pressed,
All of them would emit a similar radio 'click'

Well, do you have any idea of what frequencies it probably emitting? I guess the phenomenon is basically what you mentioned, but I still want to get an antenna and figure out if there's any way to determine the differences between the keys. What type of antenna should I buy? Will regular RF antenna be good, in your opinion?
 
Not surprised it's been done. Way back in the 1980s there was concern that it was possible to read a CRT display by decoding it's electromagnetic emissions at a distance. If I remember correctly it was even demonstrated on a UK TV program. Obviously it was much easier back then when monitors were similar to TV's.
 
The keyboard is scanned row by row. Those scan pulses generate electromagnetic waves. If a key is pressed, it changes the corresponding scan pulse slightly - and that can be picked up remotely by a sensitive receiver. Knowing the row scan sequence allows you to guess what key is pressed.

This is very general, but it is what I was told when the military wanted a keyboard that could not be tapped remotely. My solution was to introduce a short pseudo-random generator in front of the row scanner, so the row sequence was undecipherable. In any case, they were satisfied and ordered a bunch of those keyboards.
 
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This sort of thing is done all the time by spies and hackers. I'm sure there's equipment on the darknet.

I could give advice, but first I would need some assurances you were using it for legal purposes. Personally I can't think of any legal purposes, but perhaps you can.

Imagine reading someone's bank password... Lucrative, but not really legal.
 
Nidum said:
Thanks a lot! This is really helpful.
Jeff Rosenbury said:
This sort of thing is done all the time by spies and hackers. I'm sure there's equipment on the darknet.

I could give advice, but first I would need some assurances you were using it for legal purposes. Personally I can't think of any legal purposes, but perhaps you can.

Imagine reading someone's bank password... Lucrative, but not really legal.
Well I'm just a 2nd year EE student seeking for some cool challenging project to start with (-:
 

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