Network Flow Watermarking Attack on Low-Latency Anonymous Communication Systems

Many proposed low-latency anonymous communication systems have used various flow transformations such as traffic padding, adding cover traffic (or bogus packets), packet dropping, flow mixing, flow splitting, and flow merging to achieve anonymity. It has long been believed that these flow transformations would effectively disguise network flows, thus achieve good anonymity. In this paper, we investigate the fundamental limitations of flow transformations in achieving anonymity, and we show that flow transformations do not necessarily provide the level of anonymity people have expected or believed. By injecting unique watermark into the inter-packet timing domain of a packet flow, we are able to make any sufficiently long flow uniquely identifiable even if 1) it is disguised by substantial amount of cover traffic, 2) it is mixed or merged with a number of other flows, 3) it is split into a number subflows, 4) there is a substantial portion of packets dropped, and 5) it...

• Type: Conference
• Year: 2007
• Where: SP
• Authors: Xinyuan Wang, Shiping Chen, Sushil Jajodia
• Keywords: Anonymous Communication Systems, Low-latency Anonymous Communication, Security Privacy, SP 2007, flow Transformation