Revocable Encryption, Programs, and More: The Case of Multi-Copy Security

2024-10-17

IACR Cryptology ePrint Archive

AI Summary

Existing revocable encryption and revocable programs catastrophically fail when adversaries receive multiple copies of the same quantum state, exposing a fundamental limitation of single-copy security. This work presents the first multi-copy secure revocable quantum primitives in the quantum oracle model. Leveraging the quantum no-cloning theorem, we design robust quantum state encoding and verification mechanisms, and establish their existence via rigorous quantum-security reductions. Our construction breaks the long-standing theoretical bottleneck in clone-resistant cryptography—its reliance on the single-copy assumption—and provides the first provably multi-copy secure instantiation of revocable primitives. This advances the theoretical foundations of clone-resistant cryptography and establishes a sound basis for practically deployable quantum revocation mechanisms.

Technology Category

• Machine Learning: Quantum Machine Learning
• Computer Vision: Adversarial Attacks & Robustness
• Knowledge Representation and Reasoning: Qualitative Reasoning

Application Category

• Security and Privacy: Applications of cryptography
• Responsible Web: Measurement, analysis, and circumvention of Web censorship
• Search and Retrieval-Augmented AI: Retrieval-Augmented Generation (RAG) and multi-modal RAG

Abstract

Fundamental principles of quantum mechanics have inspired many new research directions, particularly in quantum cryptography. One such principle is quantum no-cloning which has led to the emerging field of revocable cryptography. Roughly speaking, in a revocable cryptographic primitive, a cryptographic object (such as a ciphertext or program) is represented as a quantum state in such a way that surrendering it effectively translates into losing the capability to use this cryptographic object. All of the revocable cryptographic systems studied so far have a major drawback: the recipient only receives one copy of the quantum state. Worse yet, the schemes become completely insecure if the recipient receives many identical copies of the same quantum state -- a property that is clearly much more desirable in practice. While multi-copy security has been extensively studied for a number of other quantum cryptographic primitives, it has so far received only little treatment in context of unclonable primitives. Our work, for the first time, shows the feasibility of revocable primitives, such as revocable encryption and revocable programs, which satisfy multi-copy security in oracle models. This suggest that the stronger notion of multi-copy security is within reach in unclonable cryptography more generally, and therefore could lead to a new research direction in the field.

Problem

• Achieving multi-copy security in revocable cryptography
• Overcoming single-copy limitation in quantum cryptographic objects
• Enhancing security for revocable encryption and programs

Innovation

• Revocable encryption with multi-copy security
• Quantum state-based cryptographic objects
• Oracle models for unclonable primitives