Confidential Computing with Quantum Cryptography
Prof. Dr. Jörn Müller-Quade (KIT Karlsruhe Kryptographie & Sicherheit)

Classical cryptographic tasks, like key distribution, need computational assumptions and are vulnerable to attacks breaking these assumptions in the future. Classical security is not everlasting. For key distribution Quantum Cryptography offers a huge advantage, unconditionally secure protocols are possible. This success, however, could not be repeated for other important cryptographic tasks, e.g. bit commitment or coin tossing. What is more, it could even be proven that all cryptographic tasks which are sufficent for confidential computing cannot be realized with unconditional security even if a quantum channel is available. This no-go result overshadowed the research on confidential computing with quantum cryptography and the term quantum cryptography is now largely seen as a synonym for quantum key distribution.

This talk shows that in spite of the no-go theorems there still are advantages of quantum cryptography over classical solutions. In particular the talk will present a yet unpublished result, that under therealistic assumption that quantum storage has a limited lifetime “everlasting security” can be achieved. I.e. computational assumptions are still needed, but the cryptographic protocol eventually becomes unconditionally secure after the quantum information used has decayed.