Not seeing is believing 
In nuclear arms control, the catchphrase “trust, but verify” gets you only so far. It's simple to count nukes deployed on intercontinental ballistic missiles, heavy bombers, or submarines: Just tally up the delivery systems. But verifying the number and types of nuclear warheads in storage—as future accords will require—is another story. No nuclear power would permit verification tests that reveal secret warhead designs. Now, there may be a solution to this conundrum. Researchers have devised a way to verify a nuclear warhead's identity without laying eyes on it. Known as a zero-knowledge protocol, a name adopted from a technique used in cryptography, their proposal is setting the arms control community abuzz.