On 2016-May-05, at 6:17 AM, Noel Chiappa wrote: >> From: Erik Baigar > >> very interesting reading > > If you want to see a great example of why it was important, check out the > so-called 'Berlin Tunnel': > > https://en.wikipedia.org/wiki/Operation_Gold > http://www.fas.org/irp/cia/product/tunnel-200702.pdf > > Some of the traffic that was intercepted was teletype traffic - which had > been encrypted. However, the equipment that connected the gear to the line > allowed a tiny electronic whisper of the original plain-text onto the line, > along with the encrypted form, and it was possible to read the plaintext off > the line with suitable gear.
A Model 28 teletype with DND (Ca. Department of National Defence) tags on it I was working on a couple years ago had been modified for what I can only presume to be TEMPEST qualification. All the standard wiring and electrical stuff - not just the current loop signal wiring but even the basic AC line wiring for the motor and such, all the way out to the wall plug - had been removed and replaced with shielded cable and connectors. The normal keyboard contacts and print selection magnets were replaced with units enclosed in shielded housings. The power line had a large noise filter in it's own RF-shielded housing.
