Quantum Cryptography beyond the “Usual” Quantum Key Distribution //

Quantum key distribution is the best-known example of cryptography whose security does not rely on assumptions about an adversary’s computational power. But quantum mechanics is not the only resource that can provide information-theoretic security, nor is key distribution the only cryptographic task which can be implemented using quantum protocols.

In this talk, we explore cryptographic protocols beyond standard QKD. We first consider secure communication based on noise in the communication channel, illustrating how physical properties other than quantum measurement disturbance can provide security. We then turn to other cryptographic tasks and ask what quantum mechanics can—and cannot—offer in this setting. Using private database queries as an example, we discuss how quantum protocols can provide mechanisms for detecting dishonest behaviour, as well as the fundamental limitations on the security that can be achieved.