Quantum Secure Key Exchange with Position-based Credentials

TL;DR

This paper develops a quantum key exchange protocol that uses location-based credentials via quantum position verification, reducing the number of verification runs needed and enhancing security analysis.

Contribution

It introduces a QKD protocol with location credentials using QPV, simplifying authentication and improving security analysis methods.

Findings

Reduced number of QPV runs for authentication

Enhanced security analysis with tighter bounds

Proposed multi-basis QPV with BB84 states

Abstract

Quantum key distribution (QKD) provides an information-theoretic way of securely exchanging secret keys, and typically relies on pre-shared keys or public keys for message authentication. To lift the requirement of pre-shared or public keys, Buhrman et. al. [SIAM J. Comput. 43, 150 (2014)] proposed utilizing the location of a party as a credential. Here, we extend upon the proposal, develop a QKD protocol with location credentials using quantum position verification (QPV) based message and identity authentication. By using QKD with delayed authentication as a base, and later simplifying QPV-based message authentication, we significantly reduce the number of QPV runs, which currently acts as a bottleneck. Besides demonstrating security for the proposed protocol, we also provide improvements to QPV security analysis, including generalization of the QPV adversary model, tightening a trace distance bound using semidefinite programming, and propose a multi-basis QPV requiring only BB84 state preparation but with multiple measurement basis.