# Robustness of implemented device-independent protocols against constrained leakage

## TL;DR

This paper analyzes the robustness of device-independent cryptographic protocols against constrained information leakage, providing new proof techniques and estimates of leakage effects on keyrates to enhance practical security assurances.

## Contribution

It introduces a tailored leakage model and compatible proof methods for analyzing recent DI protocol demonstrations, improving understanding of leakage tolerance.

## Key findings

- Leakage impacts on keyrates are quantitatively estimated.
- The new proof structure is compatible with recent DI protocols.
- Protocols can tolerate certain leakage levels while maintaining positive keyrates.

## Abstract

Device-independent (DI) protocols have experienced significant progress in recent years, with a series of demonstrations of DI randomness generation or expansion, as well as DI quantum key distribution. However, existing security proofs for those demonstrations rely on a typical assumption in DI cryptography, that the devices do not leak any unwanted information to each other or to an adversary. This assumption may be difficult to perfectly enforce in practice. While there exist other DI security proofs that account for a constrained amount of such leakage, the techniques used are somewhat unsuited for analyzing the recent DI protocol demonstrations. In this work, we address this issue by studying a constrained leakage model suited for this purpose, which should also be relevant for future similar experiments. Our proof structure is compatible with recent proof techniques for flexibly analyzing a wide range of DI protocol implementations. With our approach, we compute some estimates of the effects of leakage on the keyrates of those protocols, hence providing a clearer understanding of the amount of leakage that can be allowed while still obtaining positive keyrates.