నైరూప్య

AUGMENTING THE SECURITY IN TOR

S.Kokilavani, G.Priyadharshini

Tor is an anonymous communication network. If more users are becoming interested in their privacy, the need for such anonymous services might increase. The second generation Onion Router designs Tor and its previous designs seem to have been under research and there have been rather recent papers on Tor’s vulnerabilities. Various lowlatency anonymous communication systems such as Tor and Anonymizer have been designed to provide anonymity service for users. In order to hide the communication of users, most of the anonymity systems pack the application data into equalsized cells (e.g., 512 B for Tor, a known real-world, circuit- based, low-latency anonymous communication network).This project defends cell-counting-based attack against Tor, which allows the attacker to confirm anonymous communication relationship among users very quickly by adopting reputation based routing allocation among the onion routers. Cell counting attacks by varying the number of cells in the target traffic at the malicious exit onion router, the attacker can embed a secret signal into the variation of cell counter of the target traffic. The embedded signal will be carried along with the target traffic and arrive at the malicious entry onion router. Then, an accomplice of the attacker at the malicious entry onion router will detect the embedded signal based on the received cells and confirm the communication relationship among users. Reputation for each Tor onion router are assigned and measured on real-time. One TOR router is competing for the available routing resources, the routing is allocated when the router completely satisfy the router’s demands, unless router’s reputation is below a certain threshold, set by the system to mark misbehaviour. In this case, competing router does not receive any routing resource, as a punishment for his zero contributions or for accessing the embedded signal through cell counting attack.