14-02-2017, 11:26 AM
Concerns about privacy and security have received increased attention with the rapid growth and public acceptance of the Internet, which has been used to create our global economy E. Anonymity has become a necessary and legitimate goal in many applications, Including anonymous browsing on the Web, location-based services (LBS), and electronic voting. In these applications, encryption alone can not maintain the anonymity required by participants. In the past, researchers have developed numerous anonymous communication systems. In general, mixing techniques can be used for message-based (high latency) or flow-based (low latency) anonymity applications. Email is a typical message-based anonymity application that has been thoroughly researched. Research on applications based on the anonymity flow has recently received great attention in order to preserve anonymity in low latency applications, including web browsing and peer-to-peer file sharing.
To degrade the anonymity service provided by anonymous communication systems, traffic analysis attacks have been studied. Existing traffic analysis attacks can be classified into two groups: passive traffic analysis and active watermarking techniques. The passive traffic analysis technique will log passively traffic and identify the similarity between the outgoing traffic of the sender and the incoming traffic of the receiver based on statistical measures. Because this type of attack is based on the correlation of the times of the messages that move through the anonymous system and does not change the characteristics of the traffic, it is also a passive synchronization attack. For example, Serjantov et al. He proposed a passive packet count scheme to observe the number of packets in a connection arriving at a merge node and leaving a node. However, they did not elaborate how packet counting could be done. To improve the accuracy of attacks, the active watermark technique has recently received a lot of attention. The idea of this technique is to actively introduce special signals (or tags) into the outgoing traffic of the sender with the intention of recognizing the signal embedded in the incoming traffic of the receiver.