Description
Date depot: 1 janvier 1900
Titre: Position based cryptography
Directeur de thèse:
Jean-Pierre TILLICH (Inria-Paris (ED-130))
Domaine scientifique: Sciences et technologies de l'information et de la communication
Thématique CNRS : Non defini
Resumé:
Position-based quantum cryptography is a recent line of work where the position of the legitimate party acts as their only credential. The simplest such primitive is position verification, where honest parties can prove that they lie at a given spatial position at a certain time. While a general no-go theorem was established (both in the classical and in the quantum settings [1, 2]), it turns out that in the quantum case, the best attacks seem to require unreasonable resources: an amount of entanglement exponential (or even doubly exponential) in some parameters of the problem. Clearly, if such bounds can be proven to be optimal, then position-based quantum cryptography would become possible for any practical purposes, thereby opening the way to many completely new applications.
The main goal of this PhD is to devise simple, practical protocols that provably require a large amount of entanglement to break. A natural solution consists in increasing the number of verifiers, without requiring them to send entangled states. A second challenge will be to investigate security in a realistic scenario where (classical) computation takes time and where the communication channels are imperfect.
[1] N. Chandran, V. Goyal, R. Moriarty,R. Ostrovsky, “Position based cryptography”. In Advances in Cryptology-CRYPTO 2009, pp. 391-407, Springer Berlin Heidelberg (2009).
[2] H. Buhrman, N. Chandran, S. Fehr, R. Gelles, V. Goyal, R. Ostrovsky, C. Schaffner, “Position-Based Quantum Cryptography: Impossibility and Constructions”. Advances in Cryptology–CRYPTO 2011, pp. 429-446, Springer Berlin Heidelberg (2011).
Doctorant.e: Chakraborty Kaushik