Program obfuscation aims to hide the inner workings of a program while preserving its functionality. In the quantum setting, recent works have obtained obfuscation schemes for specialized classes of quantum circuits. For instance, Bartusek, Brakerski, and Vaikuntanathan (STOC 2024) constructed a quantum state obfuscation scheme, which supports the obfuscation of quantum programs represented as quantum states for pseudo-deterministic quantum programs with classical inputs and outputs in the classical oracle model. In this work, we improve upon existing results by constructing the first quantum state obfuscation scheme for unitary (or approximately unitary) quantum programs supporting quantum inputs and outputs in the classical oracle model. At the core of our obfuscation scheme are two novel ingredients: a functional quantum authentication scheme that allows key holders to learn specific functions of the authenticated quantum state with simulation-based security, and a compiler that represents an arbitrary quantum circuit as a projective linear-plus-measurement quantum program described by a sequence of non-adaptive Clifford gates interleaved with adaptive and compatible measurements.

翻译：程序混淆旨在隐藏程序的内部实现细节，同时保持其功能完整性。在量子计算领域，近期研究已针对特定类型的量子电路提出了混淆方案。例如，Bartusek、Brakerski和Vaikuntanathan（STOC 2024）构建了一种量子态混淆方案，该方案支持在经典预言机模型下对具有经典输入输出的伪确定性量子程序所对应的量子态进行混淆。本工作通过构建首个支持量子输入输出的酉（或近似酉）量子程序量子态混淆方案，在经典预言机模型下改进了现有成果。我们混淆方案的核心包含两个创新要素：一种功能性量子认证方案，允许密钥持有者以基于模拟的安全性学习认证量子态的特定函数；以及一个编译器，可将任意量子电路表示为由非自适应Clifford门与自适应兼容测量交错序列描述的射影线性加测量量子程序。