#h00t: Censorship Resistant Microblogging

TL;DR

#h00t introduces a censorship-resistant microblogging system that uses short hashes and collisions to enable groups to communicate securely and evade censorship, leveraging encryption and hash collisions for privacy and resilience.

Contribution

The paper proposes a novel microblogging system that employs hash collisions and encryption to resist censorship and protect group communications.

Findings

Feasibility of real-time encryption of Twitter data on a single computer.

Analysis of bandwidth and anonymity tradeoffs in hashtag collision strategies.

Demonstration that hash collisions can be used to tunnel messages and evade censorship.

Abstract

Microblogging services such as Twitter are an increasingly important way to communicate, both for individuals and for groups through the use of hashtags that denote topics of conversation. However, groups can be easily blocked from communicating through blocking of posts with the given hashtags. We propose #h00t, a system for censorship resistant microblogging. #h00t presents an interface that is much like Twitter, except that hashtags are replaced with very short hashes (e.g., 24 bits) of the group identifier. Naturally, with such short hashes, hashtags from different groups may collide and #h00t users will actually seek to create collisions. By encrypting all posts with keys derived from the group identifiers, #h00t client software can filter out other groups' posts while making such filtering difficult for the adversary. In essence, by leveraging collisions, groups can tunnel their posts in other groups' posts. A censor could not block a given group without also blocking the other groups with colliding hashtags. We evaluate the feasibility of #h00t through traces collected from Twitter, showing that a single modern computer has enough computational throughput to encrypt every tweet sent through Twitter in real time. We also use these traces to analyze the bandwidth and anonymity tradeoffs that would come with different variations on how group identifiers are encoded and hashtags are selected to purposefully collide with one another.