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Sniffing keystrokes via laser and keyboard power

Sniffing keystrokes via laser and keyboard power
Sniffing keystrokes via laser and keyboard power 

By Elinor Mills
CNet News
March 19, 2008

VANCOUVER, B.C. -- Presenters at the CanSecWest security conference 
detailed on Thursday how they can sniff data by analyzing keystroke 
vibrations using a laser trained on a shiny laptop or through electrical 
signals coming from a PC connected to a PS/2 keyboard and plugged into a 

Using equipment costing about $80, researchers from Inverse Path were 
able to point a laser on the reflective surface of a laptop between 50 
feet and 100 feet away and determine what letters were typed.

Chief Security Engineer Andrea Barisani and hardware hacker Daniele 
Bianco used a handmade laser microphone device and a photo diode to 
measure the vibrations, software for analyzing the spectrograms of 
frequencies from different keystrokes, as well as technology to apply 
the data to a dictionary to try to guess the words. They used a 
technique called dynamic time warping that's typically used for speech 
recognition applications, to measure the similarity of signals.

Line-of-sight on the laptop is needed, but it works through a glass 
window, they said. Using an infrared laser would prevent a victim from 
knowing they were being spied on.

The only real way to mitigate against this type of spying would be to 
change your typing position and mistype words, Barisani said.


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