Hordes: a Multicast-Based Protocol for Anonymity

With widespread acceptance of the Internet as a public medium for communication and information retrieval, there has been rising concern that the personal privacy of users can be eroded by cooperating network entities. A technical solution to maintaining privacy is to provide anonymity. We present a protocol for initiator anonymity called Hordes, which uses forwarding mechanisms similar to those used in previous protocols for sending data, but is the first protocol to make use of multicast routing to anonymously receive data. We show this results in shorter transmission latencies and requires less work of the protocol participants, in terms of the messages processed. We also present a comparison of the security and anonymity of Hordes with previous protocols, using the first quantitative definition of anonymity and unlinkability. Our analysis shows that Hordes provides anonymity in a degree similar to that of Crowds and Onion Routing, but also that Hordes has numerous performance advantages.