Title | Quantum-Access-Secure Message Authentication via Blind-Unforgeability |

Publication Type | Journal Article |

Year of Publication | 2020 |

Authors | Alagic, G, Majenz, C, Russell, A, Song, F |

Journal | In: Canteaut A., Ishai Y. (eds) Advances in Cryptology – EUROCRYPT 2020. Lecture Notes in Computer Science, Springer, Cham |

Volume | 12-17 |

Pages | 788-817 |

Date Published | 5/1/2020 |

Type of Article | inproceedings |

Abstract | Formulating and designing authentication of classical messages in the presence of adversaries with quantum query access has been a longstanding challenge, as the familiar classical notions of unforgeability do not directly translate into meaningful notions in the quantum setting. A particular difficulty is how to fairly capture the notion of “predicting an unqueried value” when the adversary can query in quantum superposition. We propose a natural definition of unforgeability against quantum adversaries called blind unforgeability. This notion defines a function to be predictable if there exists an adversary who can use “partially blinded” oracle access to predict values in the blinded region. We support the proposal with a number of technical results. We begin by establishing that the notion coincides with EUF-CMA in the classical setting and go on to demonstrate that the notion is satisfied by a number of simple guiding examples, such as random functions and quantum-query-secure pseudorandom functions. We then show the suitability of blind unforgeability for supporting canonical constructions and reductions. We prove that the “hash-and-MAC” paradigm and the Lamport one-time digital signature scheme are indeed unforgeable according to the definition. To support our analysis, we additionally define and study a new variety of quantum-secure hash functions called Bernoulli-preserving. Finally, we demonstrate that blind unforgeability is strictly stronger than a previous definition of Boneh and Zhandry [EUROCRYPT ’13, CRYPTO ’13] and resolve an open problem concerning this previous definition by constructing an explicit function family which is forgeable yet satisfies the definition. |

DOI | 10.1007/978-3-030-45727-3_27 |