On Wed, Jun 20, 2007 at 06:14:07PM +0200, Karel Kulhavy wrote:

quoted text
> > And guess what. Keyboards use a serial protocol. Which means that

> > there will be slightly different voltage drops in the system varying

>

> The capacitors and regulator which are made to keep the voltage almost constant

> with a swing of tens of amperes (60W/1.5V=40A) will not permit a measurable

> swing when you change the current draw by a milliamp or so. The precision of

> voltage measurement is too low for this and the noise from other permanently

> running sources too high.

This kind of security design is assuming favourable constellation of

uncontrollable environmental noises to scramble the information we are

knowingly leaking. It's basically a snake oil. We have no proof that

under every conceivable circumstances the noises will be present in a

way that completely masks the information leak.
--

Darrin Chandler            |  Phoenix BSD User Group  |  MetaBUG

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