On Wednesday 20 June 2007 12:28:28 Darrin Chandler wrote: > On Wed, Jun 20, 2007 at 06:14:07PM +0200, Karel Kulhavy wrote: > > > 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.
Karel, If you want to control the keyboard, look for the TEMPEST standard for emi/rf reduction. I'm sure the standard has been leaked by now. That will solve your fears of folks getting data from it. --STeve Andre'
