Feasibility of Mix Networks for Instant Messaging

Abstract

Private messaging has seen widespread interest in the recent years. While end-to-end encryption is widely adopted among messengers now, metadata analysis can be used unrestrictedly. To prevent accumulation of metadata at providers and network links, the traffic they route needs to be anonymous and unlinkable to any potential sender or receiver. Mix networks are an anonymous communication network design that has been studied academically since 1981. The traditional use case was Email-like, asynchronous one-to-one communication that is used without any context other than the one provided in the message itself.One problem of mix networks was unpredictable delivery delay which made these systems unpractical. Recent research has been putting uses of mix networks closer to that of traditional messaging.In this work feasibility of Instant Messaging over mix networks is analyzed with regards to its usability (i.e. the introduced delays), the anonymity of users and the security.