Waiting for Anonymity: Understanding Delays in the Tor Overlay

Although Tor is the most widely used overlay for providing anonymity services, its users often experience very high delays. Because much of Tor usage is for Web applications, which are sensitive to latency, it is critical to reduce delays in Tor. To take an important step in this direction, the authors seek an in-depth understanding of delays in Tor. By taking snapshots of the entire Tor network within a short time window, they are able to study the delay distribution of the entire router population. They also monitor delays introduced by individual Tor routers over extended periods of time. The results indicate that apart from delays introduced by routers, overlay network latency also plays a significant role in delays in Tor.