关键词: 量子密钥分配, 认证密钥更新, 有限长密钥, 可组合安全性, 信息泄露, 密钥使用寿命

Abstract: Partially information leakages of generation key undoubtedly influence the security of practical Quantum Key Distribution (QKD) system. In this paper, based on finitekey analysis and deep investigation on privacy amplification, we present a method to characternize information leakages gained by adversary in each authentication round and take the theory derived by Cederlf and Larsson into practical case. As the authentication key is fed from one round of generation keys to the next except the first round, by considering its security weakness due to information leakages and finite size effect, we further propose a universal formula for calculating the lifetime of initial authentication key used in QKD with finite resources. Numerical simulations indicate that our bound for estimating information leakages strictly characterizes the stability of practical QKD against informationleakage based attacks and our calculation formula in terms of lifetime can precisely evaluate the usage time of initial authentication key. Our work provides a practical solution for evaluating authentication security of QKD.

Key words: quantum key distribution (QKD), authentication key, finite-length key, composable security, information leakages, key lifetime