Information, Computer and Network Security Terms Glossary and
Onion Routing is a technique for pseudonymous (or anonymous) communication over a computer network, developed by David Goldschlag, Michael Reed, and Paul Syverson. The goal of Onion Routing (OR) is to protect the privacy of the sender and recipient of a message, while also providing protection for message content as it traverses a network. Onion Routing accomplishes this according to the principle of Chaum's Mix Cascades: messages travel from source to destination via a sequence of proxies ("onion routers"), which re-route messages in an unpredictable path. To prevent an adversary from eavesdropping on message content, messages are encrypted between routers. The advantage of Onion Routing (and Mix Cascades in general) is that it is not necessary to trust each cooperating Router; if one or more routers are compromised, anonymous communication can still be achieved.