SaTor: Satellite Routing in Tor to Reduce Latency

High latency is a critical limitation within the Tor network that has a negative impact on privacy conscious web users' experience and 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. To address this issue, a common strategy 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 SaTor, a latency-reducing scheme for Tor using satellite routing technology. SaTor proposes equipping Tor relays with satellite network access, utilizing satellite transmission to accelerate slow circuits, without biasing the existing path selection process. Our SaTor 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 27.6ms for over 35% of circuits in general cases, and 450ms during the slowest times, with the top 1k 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.