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Cryptography in the Age of Quantum Computers
Mark Zhandry
Wednesday, September 30, 2015, 1:00-2:00 pm Calendar
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Abstract

It is well established that full-fledged quantum computers, when realized, will completely break many of today`s cryptosystems. This looming threat has led to the proposal of so-called "post-quantum" systems, namely those that appear resistant to quantum attacks. We argue, however, that the attacks considered in prior works model only the near future, where the attacker may be equipped with a quantum computer, but the end-users implementing the protocols are still running classical devices.

Eventually, quantum computers will reach maturity and everyone — even the end-users — will be running quantum computers. In this event, attackers can interact with the end-users over quantum channels, opening up a new set of attacks that have not been considered before. In this talk, I will put forward new security models and new security analyses showing how to ensure security against such quantum channel attacks. In particular, these analyses allow for re-building many core cryptographic functionalities, including pseudorandom functions, encryption, digital signatures, and more, resulting in the first protocols that are safe to use in a ubiquitous quantum computing world. Along the way, we resolve several open problems in quantum query complexity, such as the Collision Problem for random functions, the Set Equality Problem, and the Oracle Interrogation Problem.

This talk is organized by Jonathan Katz