Examining Web censorship worldwide

Censorship is a touchy subject in America, but it’s a part of everyday life in other countries.
Assistant Professor of Computer Science Jed Crandall and Ph.D student Jong Chun Park have been working to understand the Chinese government’s methods of Internet censorship. The two will present their findings in Genoa, Italy this summer at the 30th International Conference on Distributed Computing Systems.

China was chosen as a focal point for research because the country has one of the most interesting censorship limitations from a technical point of view, Crandall said.

“We are more interested in the exact details of how censorship is done around the world and what is censored at the individual level, because that gives us a more detailed view of how censorship is implemented and the things that it is used for,” he said.
Park said he focused on where the Chinese government’s censors are located between server and client.
“The basic idea is that when a person in China tries to access a server outside of China, determining whose IP address is located where,” he said. “Certain ones are blocked by China’s government, so we are trying to figure out how those specific pages are blocked and how effective the blocking is.”

Understanding the implications and technicalities of censorship is becoming increasingly important, Crandall said.
“The Internet was originally conceived as something that didn’t really have borders, but what we are seeing is increasingly countries like Australia, New Zealand, lots of European countries, countries in the Middle East (and) China are basically setting up borders around their Internet and filtering content for various reasons,” he said.

Crandall said researchers are working to understand the various filtering methods.
“We want to understand those because it tells us what direction censorship might go,” he said. “Certain governments tend to use Internet censorship in ways that affect U.S. interests and we can always expect that there are going to be proposals of censorship here, so the more we understand it the more we can make good decisions in the future.”

China’s government has tried various methods of information filtering in the past few years,
Park said.

“China was initially trying to have a centralized mechanism to control the whole country’s Internet,” he said. “They tried to block the information in a central way because if you have a central mechanism it is easy to implement all their policies. You can have a consistent view throughout the whole country, but what we found is that mechanism is so ineffective.”
But now, Crandall said, a more localized approach is being used.

“The centralized method was difficult for them to do technically, so now they are going with an implementation that technically is more feasible, but they don’t have the centralized control anymore,” he said. “We believe they are now using a program called Blue Shield, with which you have to put a filter on every network so every university, every apartment building has to have its own filter.”
The Internet is a complex puzzle, Crandall said, one that it is difficult to solve.

“The topology of the Internet looks a lot like the highway system,” he said. “High bandwidth links are like interstates that connect cities, and then there are the more local roads.”