24.04.2019 10:00-11:00

# Boneh, Dagdelen, Fischlin, Lehmann, Schaffner, Zhandry: „Random Oracles in a Quantum World“

## 24.04.2019, 10:00

Speaker: Patrick Struck, TU Darmstadt | Location: Mornewegstraße 32 (S4|14), Room 5.3.01, Darmstadt

Organizer: Christian Janson**Abstract**

This talk is the first one in the seminar series „Reading the Crypto Classics“ for the summer term 2019. The idea of this seminar is to jointly read classical milestone papers in the area of cryptography, to discuss their impact and understand their relevance for current research areas. The seminar is running as an Oberseminar, but at the same time meant to be a joint reading group seminar of the CROSSING Special Interest Group on Advanced Cryptography with all interested CROSSING members being invited to participate.

This issue will cover the paper Boneh, Dagdelen, Fischlin, Lehmann, Schaffner, Zhandry: „Random Oracles in a Quantum World“ (ASIACRYPT 2011), DOI: 10.1007/978-3-642-25385-0_3 with the following abstract:

„The interest in post-quantum cryptography — classical systems that remain secure in the presence of a quantum adversary — has generated elegant proposals for new cryptosystems. Some of these systems are set in the random oracle model and are proven secure relative to adversaries that have classical access to the random oracle. We argue that to prove post-quantum security one needs to prove security in the quantum-accessible random oracle model where the adversary can query the random oracle with quantum state.

We begin by separating the classical and quantum-accessible random oracle models by presenting a scheme that is secure when the adversary is given classical access to the random oracle, but is insecure when the adversary can make quantum oracle queries. We then set out to develop generic conditions under which a classical random oracle proof implies security in the quantum-accessible random oracle model. We introduce the concept of a history-free reduction which is a category of classical random oracle reductions that basically determine oracle answers independently of the history of previous queries, and we prove that such reductions imply security in the quantum model. We then show that certain post-quantum proposals, including ones based on lattices, can be proven secure using history-free reductions and are therefore postquantum secure. We conclude with a rich set of open problems in this area.“**Further information**