SaTor: Exploring Satellite Routing in Tor to Reduce Latency

TL;DR

SaTor introduces satellite-assisted routing in Tor to significantly reduce latency by accelerating circuit transmission without compromising routing randomness or security.

Contribution

The paper proposes SaTor, a satellite-enabled scheme that reduces Tor latency while maintaining security, supported by simulation and real-world measurements.

Findings

SaTor achieves an average speed-up of 21.8 ms for over 40% of circuits.

Satellite access to top relays effectively reduces circuit latency.

SaTor maintains Tor's routing randomness, preserving user anonymity.

Abstract

High latency is a critical limitation within the Tor network that has a negative impact on web application responsiveness. A key factor exacerbating Tor latency is the creation of lengthy circuits that span across geographically distant regions, causing significant transmission delays. A common solution involves modifying Tor's circuit-building process to reduce the likelihood of selecting lengthy circuits. However, this strategy compromises Tor's routing randomness, increasing the risk of deanonymization. Reducing Tor's latency while minimizing security degradation presents a challenge. This paper proposes and investigates SaTor, a satellite-assisted routing scheme to reduce Tor latency. By equipping Tor relays with satellite network access, SaTor could accelerate slow circuits via satellite transmission, without biasing the existing path selection process. Our performance evaluation, using a simulator we developed along with real-world measurements, shows that over the long term, SaTor provides an expected speed-up of 21.8 ms for over 40% of circuits, with only 100 top relays equipped with satellite service. Our research uncovers a viable way to overcome Tor's latency bottleneck, serving as a practical reference for its future enhancement.