A Different World

The solution: a distributed, anonymous network

Tor helps to reduce the risks of both simple and sophisticated traffic analysis by distributing your transactions over several places on the Internet, so no single point can link you to your destination. The idea is similar to using a twisty, hard-to-follow route in order to throw off somebody who is tailing you—and then periodically erasing your footprints. Instead of taking a direct route from source to destination, data packets on the Tor network take a random pathway through several servers that cover your tracks so no observer at any single point can tell where the data came from or where it's going.





To create a private network pathway with Tor, the user's software or client incrementally builds a circuit of encrypted connections through servers on the network. The circuit is extended one hop at a time, and each server along the way knows only which server gave it data and which server it is giving data to. No individual server ever knows the complete path that a data packet has taken. The client negotiates a separate set of encryption keys for each hop along the circuit to ensure that each hop can't trace these connections as they pass through.

Once a circuit has been established, many kinds of data can be exchanged and several different sorts of software applications can be deployed over the Tor network. Because each server sees no more than one hop in the circuit, neither an eavesdropper nor a compromised server can use traffic analysis to link the connection's source and destination. Tor only works for TCP streams and can be used by any application with SOCKS support.

For efficiency, the Tor software uses the same circuit for connections that happen within the same minute or so. Later requests are given a new circuit, to keep people from linking your earlier actions to the new ones.