Simultaneous Haar Indistinguishability with Applications to Unclonable Cryptography

Understand

Unclonable cryptography is concerned with leveraging the no-cloning principle to build cryptographic primitives that are otherwise impossible to achieve classically.

• Understanding the feasibility of unclonable encryption, one of the key unclonable primitives, satisfying indistinguishability security in the plain model has been a major open question in the area.
• So far, the existing constructions of unclonable encryption are either in the quantum random oracle model or are based on new conjectures.
• We present a new approach to unclonable encryption via a reduction to a novel question about nonlocal quantum state discrimination: how well can non-communicating -- but entangled -- players distinguish between different distributions over quantum states? We call this task simultaneous state indistinguishability.