On Wed, 11 Oct 2000, jim bell wrote:
A popular, but false, myth. The video cards radiate more than the CRT's. Laptops tend to be the worst offenders.
--Lucky Green <shamrock@cypherpunks.to>
As to the video cards... Sorry, Lucky, but you're going to have to support this a little better. Emissions are a function of the signal voltage in a conductor, and the extent that this conductor is free to emit.
Given that a laptop uses an LCD display, there's really no good reason, electronically speaking, why its video hardware should have to do the ((scan+horizontal_retrace)*+vertical_retrace) sequence that the technology for getting a coherent signal relies upon. But the fact is, laptop hardware does write bits in a predefined order, (in fact the same order as CRT-based machines) so it's a worthwhile question whether anyone can figure the order and pick up the emissions from the video hardware. This looks like the sort of thing that can be resolved by experiment though; Anybody got enough DSP smarts to put an induction coil next to a laptop monitor and *see* whether they can read the darn thing? Also, it looks like the sort of thing that could be designed around. If someone were building a "secure laptop" they could make a video system and drivers that wrote the bits in a different, randomized order each time, and which only wrote the changed bits. If anybody is actually making a product like this, it would be a strong indication that *somebody* with money to spend on R&D considers it a valid threat model, because nobody makes products without a market. Bear