Paper 2025/1880

Copy-Protection from Unclonable Puncturable Obfuscation, Revisited

Abstract

Quantum copy-protection is a functionality-preserving compiler that transforms a classical program into an unclonable quantum program. This primitive has emerged as a foundational topic in quantum cryptography, with significant recent developments. However, characterizing the functionalities that can be copy-protected is still an active and ongoing research direction. Assuming the existence of indistinguishability obfuscation and learning with errors, we show the existence of copy-protection for a variety of classes of functionalities, including puncturable cryptographic functionalities and subclasses of evasive functionalities. This strictly improves upon prior works, which were either based on the existence of heuristic assumptions [Ananth and Behera CRYPTO'24] or were based on the classical oracle model [Coladangelo and Gunn STOC'24]. Moreover, our constructions satisfy a new and much stronger security definition compared to the ones studied in the prior works. To design copy-protection, we follow the blueprint of constructing copy-protection from unclonable puncturable obfuscation (UPO) [Ananth and Behera CRYPTO'24] and present a new construction of UPO by leveraging the recently introduced techniques from [Kitagawa and Yamakawa TCC'25].

Note: This article is a merger of the following two works, and subsumes both the works: [ABH25] (https://eprint.iacr.org/2025/1207.pdf) and [KY25] (https://eprint.iacr.org/2025/1264.pdf).