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

摘要： 针对密钥信息泄露影响实际量子密钥分配(quantum key distribution, QKD)系统安全性的问题，基于有限长密钥分析方法，给出了认证密钥更新过程中密钥信息泄露的刻画方法，分析了密钥有限长条件下信息泄露对实际QKD系统认证安全性带来的影响.进一步围绕密钥有限长导致认证密钥安全强度的递减问题，基于实际QKD系统的密钥信息泄露和可组合安全性，提出了初始认证密钥的使用寿命分析方法，给出了密钥有限长条件下初始认证密钥使用寿命的计算表达式；数值模拟表明，提出的信息泄露计算方法严格刻画了实际QKD系统抵抗基于信息泄露攻击的能力，给出的使用寿命计算方法能更加准确地度量初始认证密钥的周期寿命.

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