Tor is the most popular anonymous communication overlay network which hides clients' identities from servers by passing packets through multiple relays. To provide anonymity to both clients and servers, Tor onion services were introduced by increasing the number of relays between a client and a server. Because of the limited bandwidth of Tor relays, large numbers of users, and multiple layers of encryption at relays, onion services suffer from high end-to-end latency and low data transfer rates, which degrade user experiences, making onion services unsuitable for latency-sensitive applications. In this paper, we present a UDP-based framework, called DarkHorse, that improves the end-to-end latency and the data transfer overhead of Tor onion services by exploiting the connectionless nature of UDP. Our evaluation results demonstrate that DarkHorse is up to 3.62x faster than regular TCP-based Tor onion services and reduces the Tor network overhead by up to 47%.

翻译：Tor是最流行的匿名通信覆盖网络，通过多跳中继传输数据包，隐藏客户端的身份信息使其不被服务器识别。为了同时向客户端和服务器提供匿名性，Tor洋葱服务通过增加客户端与服务器之间的中继数量来实现。由于Tor中继带宽有限、用户数量庞大以及各中继节点上的多层加密机制，洋葱服务面临高端到端延迟和低数据传输速率的困境，这导致用户体验下降，使得洋葱服务不适用于对延迟敏感的应用。本文提出了一种名为DarkHorse的基于UDP的框架，通过利用UDP的无连接特性，改善Tor洋葱服务的端到端延迟及数据传输开销。评估结果表明，与基于常规TCP的Tor洋葱服务相比，DarkHorse的响应速度最高提升3.62倍，同时降低Tor网络开销达47%。