MassBrowser: Unblocking the Censored Web for the Masses, by the Masses

Abstract

Existing censorship circumvention systems fail to offer reliable circumvention without sacrificing their users' QoS and privacy, or undertaking high costs of operation. We have designed and implemented a censorship circumvention system, MassBrowser, whose goal is to offer effective censorship circumvention to a large mass of censored users, with a high quality of service (QoS), low cost of operation, and adjustable privacy protection. Towards this, we have made several key decisions in designing our system. First, we argue that circumvention systems should not bundle strong privacy protections (like anonymity) with censorship circumvention. Additional privacy properties should be offered to the users of circumvention systems as optional features which can be enabled by specific users or on specific connections (perhaps by trading off some QoS). Second, we have engineered MassBrowser by combining various state-of-the-art circumvention techniques to ensure strong censorship resilience at a very low cost of operation (i.e., $0.0001 per censored client per month when deployed at a large scale). In particular, MassBrowser aims at increasing the collateral damage of censorship by employing a “mass” of normal Internet users, from both censored and non-censored areas, to serve as circumvention proxies. Also, MassBrowser uses various techniques, like CDNBrowsing, to optimize the loads on circumvention proxies. We have built and deployed MassBrowser as a fully operational system with end-user GUI software for major operating systems. Our system has been in the beta release mode for over a year with hundreds of invited users from major censored countries testing it on a daily basis.