Delay Anonymity Tradeoff in Mix Networks: Optimal Routing
Delay Anonymity Tradeoff in Mix Networks: Optimal Routing
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混合网络中的延迟匿名权衡：最优路由
DOI：
10.1109/tnet.2016.2624023
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发表时间：
2017
期刊：
影响因子：
--
通讯作者：
P. Venkitasubramaniam
中科院分区：
文献类型：
--
作者：
O. Javidbakht;P. Venkitasubramaniam
互联网上的匿名系统旨在保护用户不向外部未经授权的实体泄露他们的身份和他们的网络活动。尽管使用了分层加密，但这些系统仍然容易受到时序分析的影响，在时序分析中，窃听者可以使用流量关联机制来识别到达目的地的数据包源。MIX是智能路由器或代理服务器，旨在通过在传输之前延迟和洗牌接收到的分组的顺序来提供来自定时分析的分组来源匿名性。这种洗牌策略自然会增加延迟，并导致在匿名性和延迟之间进行权衡。本文通过推导最大化匿名和延迟加权和的信源的最优路由，研究了混合网络中的这种权衡。对一般的多径模型可实现的匿名性进行了解析刻画，证明了在轻流量条件下，存在唯一的单路由策略，它实现了最优的延迟匿名性折衷。提出了一种低复杂度的算法，该算法可以得到最优的路径以达到期望的折衷。对于现有的实用匿名系统的图形模型，对轻流量的结果进行了特化，并刻画了此类网络规模的最优标度行为。在交通繁忙的情况下，对于不同路径上的任何速率分配，都可以实现最优匿名性。对算例网络的仿真结果表明，在轻交通条件下得到的最优路径在一般交通条件下具有较好的性能。
Anonymous systems on the Internet aim to protect users from revealing to an external unauthorized entity their identities and their network activities. Despite using layered encryption, these systems are still vulnerable to timing analysis, wherein an eavesdropper can use traffic correlation mechanisms to identify the source of packets arriving at a destination. Mixes are intelligent routers or proxy servers that aim to provide packet source anonymity from timing analysis by delaying and shuffling the order of received packets prior to transmission. Such shuffling strategies naturally increase latency and result in a tradeoff between anonymity and latency. This paper investigates this tradeoff in a network of mixes, by deriving the optimal routing for sources which maximizes weighted sum of anonymity and delay. The achievable anonymity is characterized analytically for a general multipath model, and it is shown that under light traffic conditions, there exists a unique single route strategy, which achieves the optimal delay anonymity tradeoff. A low complexity algorithm is presented that derives the optimal routes to achieve a desired tradeoff. The light traffic results are specialized for a graphical model of existing practical anonymous systems, and optimal scaling behavior with the size of such networks is characterized. In the heavy traffic regime, it is shown that optimal anonymity is achieved for any allocation of rates across the different routes. Simulations on example networks are presented where it is shown that the optimal routes derived under light traffic performs quite well in general traffic regime.