Code Obfuscation in a Quantum World

Program obfuscation is a central building block in cryptography and has been conjectured to be crypto-complete: It subsumes virtually all known cryptographic primitives, and extends the scope of cryptography with new capabilities. Yet, when bringing quantum computation into the picture, our understanding of obfuscation is inadequate: (i) On the one hand, quantum algorithms break most known constructions of obfuscation, and the few that survive are based on poorly understood computational assumptions. (ii) On the other hand, obfuscation is limited to classical programs and thus fails to cater the potential advantages of quantum computation. The notion of obfuscation of quantum programs is largely unexplored. At present, we do not even know a heuristic construction of quantum obfuscation, let alone a provably-secure one.The goal of this research program is to place obfuscation on firm footing, even in a quantum world. We will develop new constructions of classical obfuscation that are provably secure against quantum algorithms. Then, using this cryptographic tool, we will systematically tackle the question of obfuscating quantum programs. Quantum obfuscation will provide the theoretical foundation for cryptography secure against quantum attacks, and will open the floodgate for new applications of cryptography in a quantum world.