The US and USSR had more than 60,000 nuclear warheads pointed at each other at the height of the Cold War. While the Non-Proliferation Treaty of 1970 and START in 1994 have shrunk that figure to around 26,000, nobody is really sure how many still exist — because nobody’s ever actually verified the number of warheads, just the delivery systems. But with a new zero-knowledge protocol, arms inspectors will soon know exactly what they’re dealing with.
Cuclear regulatory agencies like the International Atomic Energy Agency toe a difficult line. They must identify and confirm the presence of nuclear warheads without revealing or discovering any information about the delivery system that houses it or the chemical makeup of the nuclear material itself (which would violate any number of state secrets). This leaves inspectors in a bit of a quandary, how do you confirm the presence of a nuclear warhead without directly inspecting the device? A team of researchers from Princeton University Plasma Physics Laboratory (PPPL) and the Department of Energy found the answer in cryptography.
The system consists of a small steel probe, a high energy particle beam and two warheads — the one being verified and a “golden warhead”, an identical model known to contain nuclear material. Inspectors bombard the golden warhead with high energy neutrons and record how many strike a particle detector situated on the other side of the missile. This provides a baseline reading with which the inspectors can compare readings from the unverified warhead. If the numbers match, the second warhead is a nuke. If the numbers differ, it’s a regular warhead.
For the rest of the story: http://www.gizmodo.com.au/2013/05/monster-machines-this-nuke-detector-will-spot-world-ending-warheads/