Device-independent uncloneable encryption

TL;DR

This paper introduces a device-independent variant of uncloneable quantum encryption allowing multiple decryption keys, with applications to quantum money and anti-piracy, achieving strong security guarantees without trusting quantum devices.

Contribution

It presents a novel device-independent uncloneable encryption scheme with multiple decryption keys and extends it to a single-decryptor scheme with perfect anti-piracy security.

Findings

Achieves device-independent security for uncloneable encryption.

Extends to a single-decryptor encryption scheme with standard security.

Provides an extractor result for a two-adversary scenario.

Abstract

Uncloneable encryption, first introduced by Broadbent and Lord (TQC 2020) is a quantum encryption scheme in which a quantum ciphertext cannot be distributed between two non-communicating parties such that, given access to the decryption key, both parties cannot learn the underlying plaintext. In this work, we introduce a variant of uncloneable encryption in which several possible decryption keys can decrypt a particular encryption, and the security requirement is that two parties who receive independently generated decryption keys cannot both learn the underlying ciphertext. We show that this variant of uncloneable encryption can be achieved device-independently, i.e., without trusting the quantum states and measurements used in the scheme, and that this variant works just as well as the original definition in constructing quantum money. Moreover, we show that a simple modification of our scheme yields a single-decryptor encryption scheme, which was a related notion introduced by Georgiou and Zhandry. In particular, the resulting single-decryptor encryption scheme achieves device-independent security with respect to a standard definition of security against random plaintexts. Finally, we derive an "extractor" result for a two-adversary scenario, which in particular yields a single-decryptor encryption scheme for single bit-messages that achieves perfect anti-piracy security without needing the quantum random oracle model.