B-Tor: Anonymous communication system based on consortium blockchain

The rapid development of the Internet has led to the increasingly prominent feature of openness and transparency of user information. Tor, which is used to protect personal privacy, is one of the most widely used anonymous communication systems with the largest number of users. However, there are many problems with Tor, such as: illegal transactions in the dark network disturbing social security, high communication delays, and security problems such as vulnerability to DOS attacks, man-in-the-middle attacks, and censorship attacks. In this paper, we design and implement a new anonymous communication system B-Tor based on the original Tor architecture model combined with the mainstream consortium blockchain architecture Fabric, which can trace illegal transactions by using the traceability feature of blockchain and group signature algorithm. The consensus algorithm mechanism in blockchain is utilized to improve the communication efficiency and increase the throughput of the system. The system utilizes the decentralized feature of blockchain to solve the security problem of Tor mentioned above. The system performance evaluation and security evaluation are given in this paper. The experiments show that the communication delay of B-Tor anonymous communication system is low, and in the 600s user loop test, the system successfully receives the consensus file 790629 times with 98% success rate, the highest throughput is 1352.8 TPS, and the average delay is 0.1s. It is verified through the experiments that the system can be affected less during DOS attacks and can recover the state quickly.