TWC: Option: Medium: Measurement-Based Design and Analysis of Censorship Circumvention Schemes

The Internet has become one of the most effective and common means of conveying expression that is likely to be controversial or suppressed. This freedom of expression is threatened by the now widespread practice of Internet censorship by both private and state interests.

The Tor network is one of several tools designed to allow users to safely and efficiently access censored content through one or more relay computers. Using these relays makes it difficult for a censor to determine what content is being accessed by whom. Unfortunately, this also makes it hard to measure the use and performance of these tools, leading to challenges in assessing the impact of the tools, and the security and performance of proposed alternatives.

This project is developing protocols and software to address these challenges, addressing three specific aims:

1. Developing and deploying cryptographic protocols that safely and privately measure and release important characteristics of the dynamics of the Tor network, including: number of users over time, user uptime and downtime distributions, user churn, network load, and exit statistics.

2. Enhancing the security and performance of Tor, using the data collected to improve evaluations.

3. Improving generic methods to circumvent relay blocking, including proxy distribution schemes, protocol steganography, and decoy routing.

The project is expected to result in widely-used datasets for evaluating censorship circumvention schemes, training of undergraduate and graduate students, and broad dissemination of free software that promotes freedom of expression on the Internet, against regimes that strongly oppose such expression.