Unclonable Encryption in the Haar Random Oracle Model

2026-03-11

AI Summary

This work addresses the problem of achieving reusable, unclonable encryption for messages of arbitrary length in the “minicrypt” setting—where one-way functions are not assumed to exist. To this end, we present the first such scheme in the Haar-random unitary oracle model, where all parties may query the unitary operator as well as its adjoint, conjugate, and transpose. By introducing a path-recording framework together with a novel “unitary reprogramming lemma,” we establish, without relying on any computational assumptions, the existence of reusable unclonable encryption satisfying the standard security notion of unclonable indistinguishability.

Technology Category

• Machine Learning: Privacy
• Reasoning under Uncertainty: Other Foundations of Reasoning under Uncertainty
• Search and Optimization: Non-convex Optimization

Application Category

• Security and Privacy: Applications of cryptography
• Responsible Web: Measurement, analysis, and circumvention of Web censorship
• User Modeling, Personalization and Recommendation: Attacks and countermeasures in recommendation systems

Abstract

We construct unclonable encryption (UE) in the Haar random oracle model, where all parties have query access to $U,U^\dagger,U^*,U^T$ for a Haar random unitary $U$. Our scheme satisfies the standard notion of unclonable indistinguishability security, supports reuse of the secret key, and can encrypt arbitrary-length messages. That is, we give the first evidence that (reusable) UE, which requires computational assumptions, exists in "micocrypt", a world where one-way functions may not exist. As one of our central technical contributions, we build on the recently introduced path recording framework to prove a natural ``unitary reprogramming lemma'', which may be of independent interest.

Problem

• Unclonable Encryption
• Haar Random Oracle
• Reusable Secret Key
• Micocrypt
• Quantum Cryptography

Innovation

• unclonable encryption
• Haar random oracle
• unitary reprogramming lemma
• path recording
• micocrypt