When a person uses Tor to bring up a Web page, the request is encrypted and sent along a random path through other Tor computers that act as relays. This obscures the originating IP (Internet protocol) address—a unique code that can be used to track down a Web user, to filter access to certain sites or services, or to build up a profile of a person’s Web use.
Generally, the process results in lag and restricts bandwidth, which deters some people from using Tor, says Chris Palmer, technology director at the Electronic Frontier Foundation. “The primary way to address that problem is to have more Tor relays in more places, connected to high-bandwidth, low-latency lines,” he explains. “Wireless routers may fit the bill well, if they can be built with the computational resources necessary to run a Tor relay of decent capacity.” Although consumer-grade routers are necessarily relatively low-powered, their capabilities have grown markedly in recent years, Palmer notes.
Tor routers could also make the entire Tor system better able to resist government attempts to block its use. An individual installation of Tor software hooks into the network by referring to a list of relays in a directory maintained by the Tor project. It is possible to block Tor by checking the same directory and preventing connections to the servers listed—a tactic apparently used by the Chinese authorities. It is possible to get around such a block, however, by configuring the Tor software to act as a “bridge,” or a private relay, that can only be discovered by word of mouth. A Tor router can also act as a bridge, and Appelbaum is considering making that a default setting.
During the protests in Iran that followed the 2009 election, the EFF campaigned for more people to act as Tor bridges to keep the government from blocking the tool, and Palmer says increasing the supply of bridges remains important. “It makes the adversary’s job more difficult when there are more possible bridges to advertise and use,” he says.
Appelbaum says, “If you have 10,000 people using these little routers, then China would have a lot more difficulty blocking Tor.”