WF-A2D: Enhancing Privacy With Asymmetric Adversarial Defense Against Website Fingerprinting

Despite the end-to-end encryption capabilities provided by network protocols such as QUIC in HTTP/3 and the additional tunneling functions offered by proxy tools like virtual private networks (VPNs) and the onion router (Tor), website fingerprinting (WF) techniques can still identify specific network services by exploiting the spatio-temporal characteristics of network traffic. Therefore, defending against WF attacks is crucial for ensuring comprehensive privacy protection for network services. Existing WF defenses typically rely on proxy-based solutions that require coordinated packet manipulations between the client and the proxy node to counteract WF attacks. These symmetric architectures cannot protect network traffic between proxy nodes and web servers from WF attacks. Furthermore, the ability to counter more powerful traffic analysis tools remains a challenging issue. In this paper, we propose WF-A2D, an asymmetric adversarial defense method against website fingerprinting for HTTP/3. WF-A2D employs a two-stage cascading adversarial learning strategy, leveraging packet direction and length patterns to enhance defense performance. Position-based perturbation vectors representing packet operations are generated for packet-by-packet manipulations to achieve real-time WF defense. Experimental results on a real-world HTTP/3-QUIC website browsing traffic dataset demonstrate that WF-A2D can achieve a defense success rate of 97.10% on average against seven state-of-the-art traffic analysis tools, while incurring less than 2% bandwidth overhead. More importantly, WF-A2D can operate independently on the client side and ensure end-to-end protection to web servers.