A Generic Security Proof for Quantum Key Distribution

TL;DR

This paper presents a universal and straightforward security proof for quantum key distribution that applies to various protocols, leveraging the quantum security of privacy amplification regardless of the adversary's quantum memory.

Contribution

It introduces a general security proof for quantum key distribution that is simpler and more broadly applicable than previous proofs.

Findings

Security proof applies to multiple protocols

Privacy amplification remains secure with quantum adversary memory

Simplifies the theoretical foundation of quantum cryptography

Abstract

Quantum key distribution allows two parties, traditionally known as Alice and Bob, to establish a secure random cryptographic key if, firstly, they have access to a quantum communication channel, and secondly, they can exchange classical public messages which can be monitored but not altered by an eavesdropper, Eve. Quantum key distribution provides perfect security because, unlike its classical counterpart, it relies on the laws of physics rather than on ensuring that successful eavesdropping would require excessive computational effort. However, security proofs of quantum key distribution are not trivial and are usually restricted in their applicability to specific protocols. In contrast, we present a general and conceptually simple proof which can be applied to a number of different protocols. It relies on the fact that a cryptographic procedure called privacy amplification is equally secure when an adversary's memory for data storage is quantum rather than classical.