The first public version of Tor, which came out in 2003, was available for anyone who cared to install it. But it worked only on open-source operating systems, and using it required at least some technical knowledge. The Electronic Frontier Foundation, the digital civil-liberties organization, funded development of a version for Windows, and soon a wider variety of users emerged. "Originally one of my big reasons for working on Tor was to provide tools for people in the West--Americans and Europeans--to let them keep their information safe from corporations and other large organizations that generally aren't very good at keeping it to themselves," says Dingledine, now 32, who is Tor's project leader. But now, he says, some police agencies use Tor to make sure that an investigation of an online scam won't be compromised by tipping the scammer off to regular site visits from a police department's computers. And some companies, he says, use it to help them prevent competitors from figuring out, say, who is scouring their online product sheets.

It quickly became clear that this diversity was crucial to the technology's success. "It's not just safety in numbers; there is safety in variety," Dingledine says. "Even if there were 100,000 FBI agents using Tor, you would know what it's for: 'You are using the FBI's anonymity system.' Even from the very beginning, part of the fun and the challenge was to take all of these different groups out there who care about what Tor provides, and put them all into the same network." To help promote wider use, its developers made Tor far easier to install. And in 2006, they developed a new feature, the Torbutton, which allows Tor users to easily turn Tor on and off while they browse with the Firefox Web browser (turning it off speeds up Internet access but removes the protections).

Global spread
Syria is an all-purpose Internet repressor. It hunts down some bloggers; a Syrian named Tariq Biasi, for example, was recently sentenced to three years in prison for "dwindling the national feeling"; he allegedly posted a comment critical of the state's security service online. Beyond going after online critics, Syria also blocks many websites--including Facebook, YouTube, and Skype--from all Web users in the nation. I spoke about Syrian censorship with another blogger, Anas Qtiesh; he sat in an Internet café in Damascus as I messaged him from my living room. Qtiesh isn't worried that he'll be tracked down, because he tends to blog about pan-Arab politics, not about criticisms of the regime. But he wants access to more of the Internet than the government permits, so the Firefox browser on his laptop sports the Torbutton. Click the button, and presto--the same Internet that everyone in America sees. To access blocked sites, his computer negotiates a series of proxies, eventually connecting to an IP address somewhere else in the world. This intermediary fetches the blocked material. "Tor brings back the Internet," he wrote.

Qtiesh has plenty of company: Tor was always of interest abroad, but word of mouth and the introduction of the easy-to-use Torbutton have helped accelerate its global spread. Zuckerman has been actively promoting Tor through his Global Voices network. So have other advocates of online free speech in Asia, China, and Africa. And these efforts have been working. Wendy Seltzer, who teaches Internet law at American University and founded Chilling Effects, a project to combat legal threats against Internet users, saw that firsthand when she traveled to Guangzhou, China, for a blogger conference last year. China is generally acknowledged as the most sophisticated Internet filterer in the world; it employs a variety of techniques, including blocking IP addresses, domain names (the text name of a website, such as www.google.com), and even Web pages containing certain keywords (Falun Gong, for example). According to one report, Chinese security forces have arrested several hundred Internet users and bloggers in the past 10 years. Seltzer says that many bloggers she met in Guangzhou were using Tor. And when she went to an Internet café there, she reports, the computers were automatically configured to run the software.