基于半马尔可夫过程的铁路时间同步网协议安全量化分析

Security Quantifying Method of Railway Time Synchronization Network Protocol Based on Semi-Markov Process

针对基于Autokey模型的铁路时间同步网协议安全性问题,考虑时间同步协议在攻击行为下的状态驻留时间为非指数分布,提出基于半马尔可夫过程的铁路时间同步协议的安全性量化分析方法。剖析基于Autokey模型的铁路时间同步协议序列执行流程,建立带有网络攻击行为的铁路时间同步协议完整性验证过程的状态变迁模型。分析协议的不安全状态与协议相关安全性指标之间的关系,得到协议各安全性相关指标与协议不安全状态的变迁概率和状态驻留时间之间的关系曲线,分析影响铁路时间同步网协议安全性的关键因素。研究结果可为铁路时间同步网信息安全维护提供借鉴。

In view of the security of network time synchronization protocol（NTP） based on the Autokey model in the railway time synchronization, the security quantifying method of the railway time synchronization protocol based on the semi Markov processes was proposed because the residence time of the protocol is typically non exponential in the attack behavior. Firstly, according to the analysis of railway time synchronization protocol execution process based on Autokey model, the state transition model of railway time synchronization protocol integrity verification process with network attack behavior was established. Secondly, based on the analysis of the relationship between the unsafe states of the protocol and the protocol related security indicators, the rela tionship curves between the safety of the relevant indicators and the transition probability and state dwell time of protocol unsafe state were obtained. Finally, the key factors influencing the security of railway time synchro nization network protocol were analyzed. The results can provide reference for the information security mainte nance of railway time synchronization network.