Tor is a network of virtual tunnels that allows people and groups to improve their privacy and security on the Internet. It also enables software developers to create new communication tools with built-in privacy features. Tor provides the foundation for a range of applications that allow organizations and individuals to share information over public networks without compromising their privacy.
Individuals use Tor to keep websites from tracking them and their family members, or to connect to news sites, instant messaging services, or the like when these are blocked by their local Internet providers. Tor’s hidden services let users publish web sites and other services without needing to reveal the location of the site. Individuals also use Tor for socially sensitive communication: chat rooms and web forums for rape and abuse survivors, or people with illnesses.
A basic problem for the privacy minded is that the recipient of your communications can see that you sent it by looking at headers. So can authorized intermediaries like Internet service providers, and sometimes unauthorized intermediaries as well. A very simple form of traffic analysis might involve sitting somewhere between sender and recipient on the network, looking at headers.
Tor can’t solve all anonymity problems. It focuses only on protecting the transport of data. You need to use protocol-specific support software if you don’t want the sites you visit to see your identifying information. For example, you can use Torbutton while browsing the web to withhold some information about your computer’s configuration.
Also, to protect your anonymity, be smart. Don’t provide your name or other revealing information in web forms. Be aware that, like all anonymizing networks that are fast enough for web browsing, Tor does not provide protection against end-to-end timing attacks: If your attacker can watch the traffic coming out of your computer, and also the traffic arriving at your chosen destination, he can use statistical analysis to discover that they are part of the same circuit.
The future of Tor
Providing a usable anonymizing network on the Internet today is an ongoing challenge. We want software that meets users’ needs. We also want to keep the network up and running in a way that handles as many users as possible. Security and usability don’t have to be at odds: As Tor’s usability increases, it will attract more users, which will increase the possible sources and destinations of each communication, thus increasing security for everyone. We’re making progress, but we need your help. Please consider running a relay or volunteering as a developer.