Device-independence for two-party cryptography and position verification

TL;DR

This paper establishes device-independent security proofs for two-party cryptography and position verification using Bell inequality violations, under physical constraints on adversaries, enhancing security assurances without trusting device specifics.

Contribution

It introduces device-independent security proofs for two-party cryptography and position verification based on Bell violations, independent of device details and under physical adversary constraints.

Findings

Security can be achieved for any Bell violation exceeding the classical limit.

Security proofs are valid for memoryless devices under physical constraints.

The approach does not rely on detailed knowledge of quantum operations.

Abstract

Quantum communication has demonstrated its usefulness for quantum cryptography far beyond quantum key distribution. One domain is two-party cryptography, whose goal is to allow two parties who may not trust each other to solve joint tasks. Another interesting application is position-based cryptography whose goal is to use the geographical location of an entity as its only identifying credential. Unfortunately, security of these protocols is not possible against an all powerful adversary. However, if we impose some realistic physical constraints on the adversary, there exist protocols for which security can be proven, but these so far relied on the knowledge of the quantum operations performed during the protocols. In this work we give device-independent security proofs of two-party cryptography and Position Verification for memoryless devices under different physical constraints on the adversary. We assess the quality of the devices by observing a Bell violation and we show that security can be attained for any violation of the Clauser-Holt-Shimony-Horne inequality.