SWEET: Serving the Web by Exploiting Email Tunnels

TL;DR

SWEET is a censorship-resistant system that uses email tunnels to reliably bypass censorship, leveraging popular email services to ensure high availability and performance for web access.

Contribution

It introduces SWEET, a novel infrastructure that encapsulates web traffic in email messages, making censorship disruption significantly more difficult.

Findings

SWEET achieves high availability by using email services.

Web pages are loaded within a few seconds using SWEET.

The system is effective across different email providers.

Abstract

Open communication over the Internet poses a serious threat to countries with repressive regimes, leading them to develop and deploy censorship mechanisms within their networks. Unfortunately, existing censorship circumvention systems do not provide high availability guarantees to their users, as censors can identify, hence disrupt, the traffic belonging to these systems using today's advanced censorship technologies. In this paper we propose SWEET, a highly available censorship-resistant infrastructure. SWEET works by encapsulating a censored user's traffic to a proxy server inside email messages that are carried over by public email service providers, like Gmail and Yahoo Mail. As the operation of SWEET is not bound to specific email providers we argue that a censor will need to block all email communications in order to disrupt SWEET, which is infeasible as email constitutes an important part of today's Internet. Through experiments with a prototype of our system we find that SWEET's performance is sufficient for web traffic. In particular, regular websites are downloaded within couple of seconds.