UBC Theses and Dissertations

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UBC Theses and Dissertations

The unbalancing act : proxy preservation for censorship resistance systems Spacek, Jodi


Internet censorship is a form of digital authoritarianism in certain countries that restrict access to the internet. Internet freedom, to a degree, is possible even in these countries by means of proxies maintained outside of the censor's boundaries. These proxies can be compromised by censors who pose as legitimate users to discover proxies. Censors are powerful adversaries and may block access to any proxy once they know about it. We propose a novel technique to address the proxy distribution problem in this thesis. We introduce the needle algorithm that preserves proxies by limiting their distribution. We show that it is a useful mechanism for both preserving proxies and maintaining client service under a censorship threat model. We examine characteristics of the needle algorithm in a simulation. Three measures are important under the censorship threat model; the enumeration or discovery of all proxies, load balancing guarantees, and the collateral damage of innocent bystanders. We compare the results of these experiments with two well-known algorithms, uniform random and power of 2 choices, as well as Tor's bridgedb proxy assignment mechanism.

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