01724nas a2200133 4500008004100000245003500041210003500076490001000111520132700121100001901448700002501467700002201492856007601514 2018 eng d00aUnforgeable Quantum Encryption0 aUnforgeable Quantum Encryption0 v108223 a

We study the problem of encrypting and authenticating quantum data in the presence of adversaries making adaptive chosen plaintext and chosen ciphertext queries. Classically, security games use string copying and comparison to detect adversarial cheating in such scenarios. Quantumly, this approach would violate no-cloning. We develop new techniques to overcome this problem: we use entanglement to detect cheating, and rely on recent results for characterizing quantum encryption schemes. We give definitions for (i) ciphertext unforgeability, (ii) indistinguishability under adaptive chosen-ciphertext attack, and (iii) authenticated encryption. The restriction of each definition to the classical setting is at least as strong as the corresponding classical notion: (i) implies   INT-CTXT , (ii) implies   IND-CCA2 , and (iii) implies   AE . All of our new notions also imply   QIND-CPA  privacy. Combining one-time authentication and classical pseudorandomness, we construct symmetric-key quantum encryption schemes for each of these new security notions, and provide several separation examples. Along the way, we also give a new definition of one-time quantum authentication which, unlike all previous approaches, authenticates ciphertexts rather than plaintexts.

1 aAlagic, Gorjan1 aGagliardoni, Tommaso1 aMajenz, Christian uhttps://www.quics.umd.edu/publications/unforgeable-quantum-encryption-001731nas a2200133 4500008004100000245003500041210003500076260001500111520136800126100001901494700002501513700002201538856003701560 2017 eng d00aUnforgeable Quantum Encryption0 aUnforgeable Quantum Encryption c2017/09/193 a

We study the problem of encrypting and authenticating quantum data in the presence of adversaries making adaptive chosen plaintext and chosen ciphertext queries. Classically, security games use string copying and comparison to detect adversarial cheating in such scenarios. Quantumly, this approach would violate no-cloning. We develop new techniques to overcome this problem: we use entanglement to detect cheating, and rely on recent results for characterizing quantum encryption schemes. We give definitions for (i.) ciphertext unforgeability , (ii.) indistinguishability under adaptive chosen-ciphertext attack, and (iii.) authenticated encryption. The restriction of each definition to the classical setting is at least as strong as the corresponding classical notion: (i) implies INT-CTXT, (ii) implies IND-CCA2, and (iii) implies AE. All of our new notions also imply QIND-CPA privacy. Combining one-time authentication and classical pseudorandomness, we construct schemes for each of these new quantum security notions, and provide several separation examples. Along the way, we also give a new definition of one-time quantum authentication which, unlike all previous approaches, authenticates ciphertexts rather than plaintexts.

1 aAlagic, Gorjan1 aGagliardoni, Tommaso1 aMajenz, Christian uhttps://arxiv.org/abs/1709.06539