Position-BasedQuantumCryptography:ImpossibilityAndConstructions

Date: 2010-11-19

Time: 11:00

Room: Minnaert 211

Speaker: Dr Christian Schaffner (CWI, Amsterdam)

Title: Position-Based Quantum Cryptography: Impossibility and Constructions

Abstract

We study position-based cryptography in the quantum setting. The aim is to use the geographical position of a party as its only credential. On the negative side, we show that if adversaries are allowed to share an arbitrarily large entangled quantum state, no secure position-verification is possible at all. On the positive side, we show that if adversaries do not share any entangled quantum state but can compute arbitrary quantum operations, secure position-verification is achievable. In models where secure positioning is achievable, we show that other position-based cryptographic schemes are possible as well, such as secure position-based authentication and position-based key agreement. (Joint work with Harry Buhrman, Nishanth Chandran, Serge Fehr, Ran Gelles, Vipul Goyal and Rafail Ostrovsky - http://arxiv.org/abs/1009.2490)