The use of anonymity networks such as Tor and similar tools can greatly enhance the privacy and anonymity of online communications. Tor, in particular, is currently the most widely used system for ensuring anonymity on the Internet. However, recent research has shown that Tor is vulnerable to correlation attacks carried out by state-level adversaries or colluding Internet censors. Therefore, new and more effective solutions emerged to protect online anonymity. Promising results have been achieved by implementing covert channels based on media traffic in modern anonymization systems, which have proven to be a reliable and practical approach to defend against powerful traffic correlation attacks. In this paper, we present TorKameleon, a censorship evasion solution that better protects Tor users from powerful traffic correlation attacks carried out by state-level adversaries. TorKameleon can be used either as a fully integrated Tor pluggable transport or as a standalone anonymization system that uses K-anonymization and encapsulation of user traffic in covert media channels. Our main goal is to protect users from machine and deep learning correlation attacks on anonymization networks like Tor. We have developed the TorKameleon prototype and performed extensive validations to verify the accuracy and experimental performance of the proposed solution in the Tor environment, including state-of-the-art active correlation attacks. As far as we know, we are the first to develop and study a system that uses both anonymization mechanisms described above against active correlation attacks.

翻译：匿名网络（如Tor及类似工具）的使用可显著提升在线通信的隐私性与匿名性。其中，Tor作为当前互联网上最广泛使用的匿名保障系统，近年来研究表明其易遭受国家级 adversaries或合谋互联网审查者实施的相关性攻击。为此，学界涌现出更有效的新型匿名保护方案。基于现代匿名化系统中媒体流量的隐蔽信道技术已展现出可靠且实用的防御能力，可有效对抗强相关性攻击。本文提出TorKameleon——一种审查规避方案，能够更好地保护Tor用户免受国家级 adversaries发起的强相关性攻击。该方案既可完全集成于Tor的可插拔传输模块，也可作为独立匿名系统运行，通过K匿名化机制将用户流量封装至隐蔽媒体信道中。我们的核心目标是防御针对Tor等匿名化网络的机器与深度学习相关性攻击。研究团队已开发TorKameleon原型系统，并在Tor环境下开展大量验证实验以评估其准确性及实验性能，测试涵盖最新主动相关性攻击方法。据我们所知，本研究首次提出并实现了一种融合上述两种匿名化机制以抵御主动相关性攻击的系统。