The largest collection of public internet censorship data ever compiled shows that even citizens of what are considered the world's freest countries aren't safe from internet censorship.
The University of Michigan team used its own Censored Planet tool, an automated censorship tracking system launched in 2018, to collect more than 21 billion measurements over 20 months in 221 countries. They recently presented a paper on the findings at the 2020 ACM Conference on Computer and Communications Security.
"We hope that the continued publication of Censored Planet data will enable researchers to continuously monitor the deployment of network interference technologies, track policy changes in censoring nations, and better understand the targets of interference," said Roya Ensafi, U-M assistant professor of electrical engineering and computer science who led the development of the tool.
Poland blocked human rights sites; India same-sex dating sites
Ensafi's team found that censorship is increasing in 103 of the countries studied, including unexpected places like Norway, Japan, Italy, India, Israel and Poland. These countries, the team notes, are rated some of the world's freest by Freedom House, a nonprofit that advocates for democracy and human rights. They were among nine countries where Censored Planet found significant, previously undetected censorship events between August 2018 and April 2020. They also found previously undetected events in Cameroon, Ecuador and Sudan.
While the United States saw a small uptick in blocking, mostly driven by individual companies or internet service providers filtering content, the study did not uncover widespread censorship. However, Ensafi points out that the groundwork for that has been put in place here.
"When the United States repealed net neutrality, they created an environment in which it would be easy, from a technical standpoint, for ISPs to interfere with or block internet traffic," she said. "The architecture for greater censorship is already in place and we should all be concerned about heading down a slippery slope."
It's already happening abroad, the researchers found.
"What we see from our study is that no country is completely free," said Ram Sundara Raman, U-M doctoral candidate in computer science and engineering and first author of the study. "We're seeing that many countries start with legislation that compels ISPs to block something that's obviously bad like child pornography or pirated content.
"But once that blocking infrastructure is in place, governments can block any websites they choose, and it's a very opaque process. That's why censorship measurement is crucial, particularly continuous measurements that show trends over time."
Norway, for example--tied with Finland and Sweden as the world's freest country, according to Freedom House--passed laws requiring ISPs to block some gambling and pornography content beginning in early 2018. Censored Planet, however, uncovered that ISPs in Norway are imposing what the study calls "extremely aggressive" blocking across a broader range of content, including human rights websites like Human Rights Watch and online dating sites like Match.com.
Similar tactics show up in other countries, often in the wake of large political events, social unrest or new laws. News sites like The Washington Post and The Wall Street Journal, for example, were aggressively blocked in Japan when Osaka hosted the G20 international economic summit in June 2019. News, human rights and government sites saw a censorship spike in Poland after protests in July 2019, and same-sex dating sites were aggressively blocked in India after the country repealed laws against gay sex in September 2018.
Censored Planet releases technical details for researchers, activists
The researchers say the findings show the effectiveness of Censored Planet's approach, which turns public internet servers into automated sentries that can monitor and report when access to websites is being blocked. Running continuously, it takes billions of automated measurements and then uses a series of tools and filters to analyze the data and tease out trends.
The study also makes public technical details about the workings of Censored Planet that Raman says will make it easier for other researchers to draw insights from the project's data, and help activists make more informed decisions about where to focus.
"It's very important for people who work on circumvention to know exactly what's being censored on which network and what method is being used," Ensafi said. "That's data that Censored Planet can provide, and tech experts can use it to devise circumventions."
Censored Planet's constant, automated monitoring is a departure from traditional approaches that rely on volunteers to collect data manually from inside countries.
Manual monitoring can be dangerous, as volunteers may face reprisals from governments. Its limited scope also means that efforts are often focused on countries already known for censorship, enabling nations that are perceived as freer to fly under the radar. While censorship efforts generally start small, Raman says they could have big implications in a world that is increasingly dependent on the internet for essential communication needs.
"We imagine the internet as a global medium where anyone can access any resource, and it's supposed to make communication easier, especially across international borders," he said. "We find that if this continues, that won't be true anymore. We fear this could lead to a future where every country has a completely different view of the internet."
The study is titled "Censored Planet: An Internet-wide, Longitudinal Censorship Observatory." The research team also included former U-M computer science and engineering student Prerana Shenoy and Katharina Kohls, an assistant professor at Radboud University in Nijmegen, Netherlands. The research was supported in part by the U.S. National Science Foundation, Award CNS-1755841.
Ram Sundara Raman