For many of Iran's dissidents trying to defy the government of Mahmoud Ahmadinejad, contact with the outside world depends on a little flash drive in Shiyu Zhou's pocket.
Zhou is a Chinese-born computer scientist. He is deputy director of the Global Internet Freedom Consortium, though the group's name makes it sound somewhat more official than it really is. It is a loose network of about 50 engineers like him, working in their free time to break down the electronic walls put up by repressive governments.
"History is often made by people who have the courage just to do it by themselves," said Michael Horowitz of the Hudson Institute, a Washington-based group that supports the consortium's work. "I think that's what these guys are doing."
The consortium operates quietly; Zhou asked us, for fear of reprisals, not to report where he lives. His true cause has been the Falun Gong spiritual movement in China. Twenty years ago, in Beijing, he was a student at the Tiananmen Square uprising, and he says it changed him.
"I realized how frightening a state-controlled media can be, that it can turn black into white overnight," he said when we met in New York.
To fight back in the Internet age, Zhou and his comrades have, among other things, devised a small computer application they call FreeGate, and that's what is stored on Zhou's flash drive. It has also been shared by hundreds of thousands of dissidents in Iran, China, Burma (also called Myanmar) and other countries that try to limit people's access to Web sites that might compromise the government's power.
To demonstrate FreeGate, Zhou plugged the flash drive into a laptop computer. In a moment, a small instruction box appeared on the screen.
The words were in English. If we had been in China or Iran, said Zhou, the program would have determined that and given us directions in Mandarin or Farsi.
"Click here," said Zhou. A Web browser opened -- unremarkable, except that the URL (the Web address) at the top was gibberish, and a box in the middle of the screen was labeled "Anonymous Surfing."
"I believe Google might be open," he said. "Try Google."
In Iran, where the Internet is more centralized than in the United States -- and therefore more easily controlled by the government -- Zhou said we would have gotten a blank screen. Instead, we were able to click on Google News for a list of headlines. We also went to the Voice of America, and other sites Zhou says are blocked by repressive governments.
FreeGate gives its users a route around government censorship, taking them to so-called proxy websites that censors do not know to block.
Key to this: the I.P. address of those sites (a number giving the site's online location) changes every few seconds. The FreeGate program keeps up with the change, but it makes the user's path very hard to trace.
Zhou and his team have been sending the program around China for several years, and government censors there, he said, have been unable to defeat it.
"Over the past few days," said Zhou, "the users from Iran have been about 400,000 every day." The traffic has been so heavy, he said, that it overwhelms the proxy websites
The Hudson Institute's Horowitz says it is essential to get public attention for FreeGate and similar programs, so that Washington will support the online insurgents and help them get more technical resources. He says the implications of what they're doing are huge -- in Iran, China, and other countries that are trying to limit freedom.
"Here's a way of undermining dictatorships like those in Iran, and most of all, here's a way of tearing down the Internet firewalls," he said.
"We all remember when the Berlin Wall collapsed and the implications of that. Well, in the 21st century, the walls are made of electrons, not of stone and barbed wire."