IMHO, if you light up two or more other identical CRT's and have them display random junk it should throw enough noise to make it worthless - (and would put out enough similar RF to mess with RF tempest) there might be ways to filter the photons from the other monitors out, but, it would be difficult. ----------------------Kaos-Keraunos-Kybernetos--------------------------- + ^ + :"Our enemies are innovative and resourceful, and so are we. /|\ \|/ :They never stop thinking about new ways to harm our country /\|/\ <--*-->:and our people, and neither do we." -G. W. Bush, 2004.08.05 \/|\/ /|\ : \|/ + v + : War is Peace, freedom is slavery, Bush is President. ------------------------------------------------------------------------- On Thu, 2 Dec 2004, Tyler Durden wrote:
Interesting. Contrary to what I thought (or what has been discussed here), only a 'scalar' of detected light is needed, not a vector. In other words, merely measuring overall radiated intensity over time seems to be sufficient to recover the message. This means that certain types of diffusive materials will not necessarily mitigate against this kind of eavesdropping.
However, his discussion would indicate that the various practical concerns and limitations probably limit this to very niche-type applications...I'd bet that it's very rare when such a trechnique is both needed as well as useful, given the time, the subject and the place.
-TD
From: Sunder <sunder@sunder.net> To: cypherpunks@al-qaeda.net Subject: Optical Tempest FAQ Date: Thu, 2 Dec 2004 10:27:04 -0500 (est)
http://www.cl.cam.ac.uk/~mgk25/emsec/optical-faq.html
Along with tips and examples.
Enjoy, and don't use a CRT in the dark. :-)