匿名通信系统不可观测性度量方法  

Towards Measuring Unobservability in Anonymous Communication Systems

作　　者：谭庆丰[1,2,3] 时金桥[1,2] 方滨兴[1,2] 郭莉[1,2] 张文涛[1,2] 王学宾[1,2] 卫冰洁[4] 

机构地区：[1]中国科学院信息工程研究所,北京100093 [2]信息内容安全技术国家工程实验室(中国科学院信息工程研究所),北京100093 [3]中国科学院大学,北京100049 [4]国家计算机网络应急技术处理协调中心,北京100029

出　　处：《计算机研究与发展》2015年第10期2373-2381,共9页Journal of Computer Research and Development

基　　金：国家科技支撑计划基金项目(2012BAH37B04);中国科学院战略性先导科技专项课题(XDA06030200)

摘　　要：匿名通信技术作为一种主要的隐私增强技术被广泛应用于互联网的各个方面,然而传统的匿名通信系统很容易被监视、检测.因此,国内外研究者一直致力于改进匿名通信系统的不可观测属性,以防范网络审查和监视.然而,如何量化评估这些协议的不可观测程度则几乎没有相关的研究.针对匿名通信系统提出一种基于相对熵的不可观测性度量方法,该方法从敌手的威胁模型出发,将匿名通信系统的输入、输出状态映射到一个交互式图灵机,并在此基础之上提出一个基于相对熵的不可观测性度量框架,该框架能够有效地度量匿名通信系统的不可观测程度.此外,将它应用于TOR匿名通信系统的传输层插件的度量,实验结果表明,该方法能够有效地度量匿名通信系统的不可观测性.Anonymous communication technique is one of the main privacy-preserving techniques,which has been widely used to protect Internet users’privacy. However,existing anonymous communication systems are particularly vulnerable to traffic analysis,and researchers have been improving unobservability of systems against Internet censorship and surveillance.However,how to quantify the degree of unobservability is a key challenge in anonymous communication systems.We model anonymous communication systems as an alternating turing machine,and analyze adversaries’threat model.Based on this model,this paper proposes a relative entropy approach that allows to quantify the degree of unobservability for anonymous communication systems. The degree of unobservability is based on the probabilities of the observed flow patterns by attackers.We also apply this approach to measure the pluggable transports of TOR,and show how to calculate it for comparing the level of unobservability of these systems.The experimental results show that it is useful to evaluate the level of unobservability of anonymous communication systems.Finally,we present the conclusion and discuss future work on measuring unobservability in anonymous communication systems.

关 键 词：匿名通信 相对熵 不可观测性 隐私保护 流分析 

分 类 号：TP311.52[自动化与计算机技术—计算机软件与理论]