An Improved DSSS-Based Flow Marking Technique for Anonymous Communication Traceback

The widely use of anonymous communication systems, which aim at protecting the privacy of Internet users, has posed significant challenges to the capability of tracing cyber crimes. To address the problems of anonymous abuse, Yu et al. recently developed a new class of flow marking technique for invisible traceback based on direct sequence spread spectrum (DSSS), utilizing a pseudo-noise (PN) code. However, there exists one limitation in this technique that the suspect flow to embed flow mark into must have a fixed traffic rate, while it´s not the case for most use of anonymous communication systems, such as Web browse, instant communication and remote login. In this paper, an improved approach is proposed, which embeds signal by modulating the statistical character of packets arriving time instead of traffic rate. The experiment results show that this new technique is effective and efficient in detecting interactive traffic through anonymous communication systems and has wider applicability compared with the original DSSS-based flow marking technique.