Quantum copy protection and unclonable cryptography

Liu, Jiahui, Ph. D.
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While quantum computers are often seen as a threat to modern cryptographic systems, if honest parties and authorities make use of quantum computers, we can develop new cryptographic protocols and applications. These protocols, such as information-theoretic key exchange, unforgeable banknotes, and position-based cryptographic protocols, rely on the unclonability of quantum information and demonstrate a quantum advantage by offering classically unachievable security guarantees. Quantum copy protection, put forward by Aaronson(CCC'09), is one important example among the new capabilities. A copy protection scheme aims at preventing adversarial users from making pirate copies of a software program. We would like to achieve such a scheme by encoding a classical functionality into a quantum state so that any user with one copy of the state can run the program, but any malicious user trying to duplicate the state would fail. In this work, we investigate the feasibility of designing provably secure quantum copy protection protocols by combining classical post-quantum cryptographic tools with quantum information.