The speakers go in depth about the methods of destructions of the Five Eyes. Once source is a Guardian laptop which contained classified material, for which the GCHQ agents insisted to witness/enforce the destruction. Trackpad chip, battery controller, CPU, the agents had a laundry list of components to destroy and tick off.

The most interesting slide to me is that a top secret document remains secret if shredded pieces are larger than 12mm, and decrease is classification until they're declassified at 3mm.

Fun part is one sysadmin who had to destroy brand new iPhones of government officials because they plugged it on a classified network for less than a minute. It matches my lightening talk on civil intelligence: When there's a wire, they're compromised. On the other hands, are we really governed by officials who plug their iPhones on secret networks?

The take away for me is: Even GCHQ gave up the hope of securing computers. If you're a big target, everything is infected. But they still believe in airgaps.