Unclonable Cryptography in the Plain Model

By leveraging the no-cloning principle of quantum mechanics, unclonable cryptography enables us to achieve novel cryptographic protocols that are otherwise impossible classically. Two most notable examples of unclonable cryptography are quantum copy-protection and unclonable encryption. Despite receiving a lot of attention in recent years, two important open questions still remain: copy-protection for point functions in the plain model, which is usually considered as feasibility demonstration, and unclonable encryption with unclonable indistinguishability security in the plain model. In this work, by relying on previous works of Coladangelo, Liu, Liu, and Zhandry (Crypto'21) and Culf and Vidick (Quantum'22), we establish a new monogamy-of-entanglement property for subspace coset states, which allows us to obtain the following new results: - We show that copy-protection of point functions exists in the plain model, with different challenge distributions (including arguably the most natural ones). - We show, for the first time, that unclonable encryption with unclonable indistinguishability security exists in the plain model.