BTQ Technologies builds a quantum key that vanishes after one use

BTQ Technologies has recently published "A quantum algorithm for one-shot signatures," the first circuit-level implementation of a new kind of cryptographic primitive: one whose single-use security is enforced not by trust or consensus but by the laws of quantum mechanics. The new system addresses a vulnerability in existing digital signatures which rely on the hardness of problems like factoring large integers, a weakness Shor's algorithm threatens with quantum computers. Unlike traditional signatures using two mathematically related keys, this scheme creates a signature verifiable with a public key but designed for one-time use only; as the company explains, it offers security "enforced not by trust or consensus but by the laws…