Exploring Tor's Activity Through Long-term Passive TLS Traffic Measurement

TitleExploring Tor's Activity Through Long-term Passive TLS Traffic Measurement
Publication TypeConference Paper
Year of Publication2016
AuthorsAmann, J., & Sommer R.
Published inProceedings of Passive and Active Measurement Conference (PAM)
Date Published03/2016

Tor constitutes one of the pillars of anonymous online communication. It allows its users to communicate while concealing from observers their location as well as the Internet resources they access. Since its rst release in 2002, Tor has enjoyed an increasing level of popularity with now commonly more than 2,000,000 simultaneous active clients on the network. However, even though Tor is widely popular, there is only little understanding of the large-scale behavior of its network clients. In this paper, we present a longitudinal study of the Tor network based on passive analysis of TLS trac at the Internet uplinks of four large universities inside and outside of the US. We show how Tor trac can be identi ed by properties of its autogenerated certi cates, and we use this knowledge to analyze characteristics and development of Tor's trac over more than three years.

ICSI Research Group

Networking and Security