# Parallel Device-Independent Quantum Key Distribution

## TL;DR

This paper proves the first parallel security protocol for device-independent quantum key distribution, reducing time-steps and security constraints, and achieving linear key rates with tolerable device imprecision.

## Contribution

It introduces a parallel execution security proof for DI-QKD, enhancing efficiency and robustness over previous sequential protocols.

## Key findings

- First parallel security proof for DI-QKD
- Reduces number of time-steps for key generation
- Achieves linear key rate with device imprecision tolerance

## Abstract

A prominent application of quantum cryptography is the distribution of cryptographic keys that are provably secure. Recently, such security proofs were extended by Vazirani and Vidick (Physical Review Letters, 113, 140501, 2014) to the device-independent (DI) scenario, where the users do not need to trust the integrity of the underlying quantum devices. The protocols analyzed by them and by subsequent authors all require a sequential execution of N multiplayer games, where N is the security parameter. In this work, we prove unconditional security of a protocol where all games are executed in parallel. Besides decreasing the number of time-steps necessary for key generation, this result reduces the security requirements for DI-QKD by allowing arbitrary information leakage of each user's inputs within his or her lab. To the best of our knowledge, this is the first parallel security proof for a fully device-independent QKD protocol. Our protocol tolerates a constant level of device imprecision and achieves a linear key rate.