Device-independent uncloneable encryption

Abstract: Uncloneable encryption, first introduced by Broadbent and Lord (TQC 2020), is a form of encryption producing a quantum ciphertext with the property that if the ciphertext is distributed between two non-communicating parties, they cannot both learn the underlying plaintext even after receiving the decryption key. In this work, we introduce a variant of uncloneable encryption in which several possible decryption keys can decrypt a particular encryption, and the security requirement is that two parties who receive independently generated decryption keys cannot both learn the underlying ciphertext. We show that this variant of uncloneable encryption can be achieved device-independently, i.e., without trusting the quantum states and measurements used in the scheme. Moreover, we show that this variant of uncloneable encryption works just as well as the original definition in constructing private-key quantum money, and that uncloneable bits can be achieved in this variant without using the quantum random oracle model.