Randomness determines practical security of BB84 quantum key distribution

TL;DR

This paper analyzes how practical security of BB84 quantum key distribution is affected by device imperfections and introduces a security proof against various practical attack models based on randomness vulnerabilities.

Contribution

It classifies practical attacks into three categories and provides a security proof for BB84 under these attack models, enhancing real-world security guarantees.

Findings

Security of BB84 holds under Trojan horse, strong randomness, and weak randomness attacks.

Practical imperfections can be systematically categorized for security analysis.

Results help in designing more secure quantum key distribution systems.

Abstract

Unconditional security of the BB84 quantum key distribution protocol has been proved by exploiting the fundamental laws of quantum mechanics, but the practical quantum key distribution system maybe hacked by considering the imperfect state preparation and measurement respectively. Until now, different attacking schemes have been proposed by utilizing imperfect devices, but the general security analysis model against all of the practical attacking schemes has not been proposed. Here, we demonstrate that the general practical attacking schemes can be divided into the Trojan horse attack, strong randomness attack and weak randomness attack respectively. We prove security of BB84 protocol under randomness attacking models, and these results can be applied to guarantee the security of the practical quantum key distribution system.