As Internet filtering and censorship soars around the world, a comprehensive examination of leading circumvention technologies--carried out partly at Internet cafes in China, Vietnam, and South Korea--concludes that the leading tools work well but can slow Internet access significantly and, in some cases, present security holes.

"The issue of performance is a big one in terms of going to a higher proportion of users in countries where there is censorship," says John Palfrey, Harvard University Internet law professor and coauthor of the report released today by Harvard's Berkman Center for Internet and Society. "As with many Internet-based tools, the issue is one of scale," Palfrey adds. "Can you create an environment where it is easy enough and protective enough for people to use these tools? If not, they will remain a fringe activity."

In a related ongoing effort, the OpenNet Initiative--a project involving Harvard, the University of Toronto, Oxford University, and Cambridge University--is studying the spread of Internet censorship and surveillance worldwide. A forthcoming report will show a sharp rise in global filtering activity. Analyzing new data from 71 countries, OpenNet researchers have so far confirmed filtering in more than three dozen--up from 25 nations found to be filtering in a 2006 report, which looked at 46 nations in total. The new analysis, which will not be concluded for several more weeks, will also show greater blocking of social-networking sites such as Facebook and YouTube; increased filtering of blogging platforms, especially in the Middle East and North Africa; and an increase in examples of Western nations trying to block pornography, hate speech, and terrorism sites.

To get around Web restrictions, Internet users can install circumvention software. Such tools employ various approaches to route information around government or ISP blocks using proxy computers, or computers in nonfiltering nations that can fetch blocked pages and pass them on. Some versions allow people in filtered nations to tap their personal networks of friends and family abroad to acquire reliable and safe proxy-computer addresses. More complex systems bounce data around a few hops, with identifying data encrypted, to protect anonymity.