CensorSpoofer: Asymmetric Communication with IP Spoofing for Censorship-Resistant Web Browsing

TL;DR

CensorSpoofer is a novel censorship-resistant web browsing framework that uses asymmetric channels and IP spoofing to hide proxy addresses, enabling users to access content without revealing their location to censors.

Contribution

It introduces a new asymmetric communication framework utilizing IP spoofing and steganography to enhance censorship resistance in web browsing.

Findings

Prototype using encrypted VoIP demonstrated feasibility.

Effective decoupling of upstream and downstream channels.

IP spoofing prevents censors from discovering proxy addresses.

Abstract

A key challenge in censorship-resistant web browsing is being able to direct legitimate users to redirection proxies while preventing censors, posing as insiders, from discovering their addresses and blocking them. We propose a new framework for censorship-resistant web browsing called {\it CensorSpoofer} that addresses this challenge by exploiting the asymmetric nature of web browsing traffic and making use of IP spoofing. CensorSpoofer de-couples the upstream and downstream channels, using a low-bandwidth indirect channel for delivering outbound requests (URLs) and a high-bandwidth direct channel for downloading web content. The upstream channel hides the request contents using steganographic encoding within email or instant messages, whereas the downstream channel uses IP address spoofing so that the real address of the proxies is not revealed either to legitimate users or censors. We built a proof-of-concept prototype that uses encrypted VoIP for this downstream channel and demonstrated the feasibility of using the CensorSpoofer framework in a realistic environment.