High latency is a critical limitation within the Tor network. 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 the randomness of Tor's routing, thereby increasing the risk of deanonymization. Improving Tor's latency performance while minimizing security degradation presents a critical challenge. This paper proposes SaTor, a latency-improving scheme for Tor using satellite routing technology. SaTor proposes equipping a targeted subset of Tor relays with satellite network access, utilizing long-distance satellite transmission to accelerate slow circuits, without biasing the existing path selection process. Our SaTor performance evaluation, using a simulator we developed coupled with real-world measurements, demonstrates that over the long-term, SaTor offers an expected speed-up of roughly 40 ms for over 70% of circuits under common conditions. This improvement necessitates outfitting the top approx. 30-40% relays with satellite access. Our research uncovers a viable way to overcome Tor's latency bottleneck, serving as a practical reference for its future enhancement.

翻译：高延迟是Tor网络面临的关键性能瓶颈。导致Tor延迟加剧的一个核心因素是跨地理远距离构建的长路径电路，这会引发显著的传输延迟。为解决该问题，现有方案通常通过修改Tor的电路构建机制来降低长路径电路的选择概率。然而，此类策略会破坏Tor路由的随机性，从而增加用户去匿名化的风险。如何在提升Tor延迟性能的同时最大限度保障安全性，成为亟待解决的重要挑战。本文提出SaTor——一种基于卫星路由技术的Tor延迟优化方案。SaTor通过为特定比例的Tor中继节点配备卫星网络接入能力，利用长距离卫星传输加速低速电路，且无需改变现有路径选择机制。我们结合自主研发的仿真器与真实测量数据对SaTor进行性能评估，结果表明：在常规条件下长期运行时，SaTor能为超过70%的电路提供约40毫秒的预期加速效果，该优化需为前约30-40%的中继节点部署卫星接入能力。本研究揭示了突破Tor延迟瓶颈的有效路径，为其未来演进提供了实践参考。