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Uncloneable Encryption

April 10, 2019 - 11:00am
Anne Broadbent
Could the no-cloning property of quantum information be used to protect ciphertexts against copying?  In 2002, Gottesman answered this question in the positive, proposing a quantum encryption scheme for classical messages, with a decryption process that detects any attempt to copy the ciphertext. Clearly, classical information alone does not allow such a functionality, since it is always possible to perfectly copy a classical ciphertext while avoiding detection. However, Gottesman left open the question of restricting the knowledge that two recipients could simultaneously have on a plaintext, after an attack on a single ciphertext.  Here, we address this open question by showing that Wiesner's conjugate coding can be used to achieve this type of uncloneable encryption for classical messages. Our approach is a prepare-and-measure scheme and the analysis is done in the quantum random oracle model, using techniques from the analysis of monogamy-of-entanglement games.
Reference: Anne Broadbent and  Sébastien Lord. Uncloneable Quantum Encryption via Random Oracles.   arXiv:1903.00130.  
PSC 1136