Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Radiation emitted by wired keyboard

  1. Apr 8, 2016 #1
    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.
  2. jcsd
  3. Apr 8, 2016 #2
    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'
  4. Apr 8, 2016 #3


    Staff: Mentor

    :wink:Too bad you can't send your question to the NSA. If it can be done, they probably did it.
  5. Apr 9, 2016 #4
    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?
  6. Apr 9, 2016 #5


    User Avatar
    Science Advisor
    Gold Member

  7. Apr 9, 2016 #6


    User Avatar
    Science Advisor
    Homework Helper
    Gold Member

    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.
  8. Apr 9, 2016 #7


    User Avatar
    Science Advisor

    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.
  9. Apr 9, 2016 #8
    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.
  10. Apr 10, 2016 #9
    Thanks a lot! This is really helpful.
    Well i'm just a 2nd year EE student seeking for some cool challenging project to start with (-:
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook

Have something to add?
Draft saved Draft deleted