Development of Anonymous Networks Based on Symmetric Key Encryptions

Anonymous networks enable entities to send messages without disclosing their identities. Many anonymous networks had been proposed already, such as Mixnet, DC-net, Crowds, etc., however, they still have serious drawbacks. Namely, they require tremendous computation overheads to transmit messages over networks. That is because asymmetric key encryption algorithms are used. This paper proposes ESEBM (Enhanced Symmetric Key Encryption based Mixnet), a new mechanism for anonymous communication that removes drawbacks of existing anonymous networks while exploiting symmetric key encryption algorithms. According to experimentations, throughput of ESEBM is about 1/4.4 of usual non-anonymous networks, and it achieves more than 36 times higher throughput compared with Mixnet. In addition, different from existing anonymous networks, ESEBM can handle reply messages without any additional mechanism, and it can protect itself from various threats, e.g. DOS attacks and message forgeries.