Ariadne: a Privacy-Preserving Network Layer Protocol

This paper presents Ariadne, a privacy-preserving network layer communication protocol using source routing to avoid relying on trusted third parties. In Ariadne, a source node willing to send anonymized network traffic to a destination uses a path consisting in nodes with which it has pre-shared symmetric keys through a setup phase. It uses temporary keys derived from those pre-shared keys to protect communication privacy using onion routing techniques. Ariadne enhances previous approaches by introducing two novelties. Firstly, the temporary keys used to process the packets on the path are referenced using mutually known encrypted patterns. This avoids the use of an explicit key reference that could be used to de-anonymize the communications. Secondly, the source route is encoded in a fixed size, sequentially encrypted vector of routing information elements, in which the elements' positions in the vector are pseudo-randomly permuted.