Quantum copy protection, introduced by Aaronson, enables giving out a quantum program-description that cannot be meaningfully duplicated. Despite over a decade of study, copy protection is only known to be possible for a very limited class of programs. As our first contribution, we show how to achieve "best-possible" copy protection for all programs. We do this by introducing quantum state indistinguishability obfuscation (qsiO), a notion of obfuscation for quantum descriptions of classical programs. We show that applying qsiO to a program immediately achieves best-possible copy protection. Our second contribution is to show that, assuming injective one-way functions exist, qsiO is concrete copy protection for a large family of puncturable programs -- significantly expanding the class of copy-protectable programs. A key tool in our proof is a new variant of unclonable encryption (UE) that we call coupled unclonable encryption (cUE). While constructing UE in the standard model remains an important open problem, we are able to build cUE from one-way functions. If we additionally assume the existence of UE, then we can further expand the class of puncturable programs for which qsiO is copy protection. Finally, we construct qsiO relative to an efficient quantum oracle.

翻译：量子复制保护由Aaronson提出，允许分发无法被有效复制的量子程序描述。尽管经过十多年研究，目前仅对极少数程序类别实现了复制保护。作为首要贡献，我们展示了如何对所有程序实现"最佳可能"复制保护。为此，我们引入了量子态不可区分性混淆(qsiO)概念——一种针对经典程序量子描述的混淆方案。研究表明，将qsiO应用于任何程序即可立即实现最佳可能复制保护。第二项贡献在于，假设单射单向函数存在，qsiO能为大批可穿孔程序类提供具体复制保护方案——显著扩展了可复制保护程序的范围。证明中的关键工具是称为耦合不可克隆加密(cUE)的新型不可克隆加密(UE)变体。尽管在标准模型中构造UE仍是重要开放问题，但我们能基于单向函数构建cUE。若进一步假设UE存在，则可扩展更多可穿孔程序类使qsiO实现复制保护。最终，我们构建了相对于高效量子神谕的qsiO方案。