Censored Planet: An Internet-wide, Longitudinal Censorship Observatory

Remote censorship measurement techniques offer capabilities for monitoring Internet reachability around the world. However, operating these techniques continuously is labor-intensive and requires specialized knowledge and synchronization, leading to limited adoption. In this paper, we introduce Censored Planet, an online censorship measurement platform that collects and analyzes measurements from ongoing deployments of four remote measurement techniques (Augur, Satellite/Iris, Quack, and Hyperquack). Censored Planet adopts a modular design that supports synchronized baseline measurements on six Internet protocols as well as customized measurements that target specific countries and websites. Censored Planet has already collected and published more than 21.8 billion data points of longitudinal network observations over 20 months of operation. Censored Planet complements existing censorship measurement platforms such as OONI and ICLab by offering increased scale, coverage, and continuity. We introduce a new representative censorship metric and show how time series analysis can be applied to Censored Planet's longitudinal measurements to detect 15 prominent censorship events, two-thirds of which have not been reported previously. Using trend analysis, we find increasing censorship activity in more than 100 countries, and we identify 11 categories of websites facing increasing censorship, including provocative attire, human rights issues, and news media. We hope that the continued publication of Censored Planet data helps counter the proliferation of growing restrictions to online freedom.