A group of human-rights advocates and computer security experts has released a Firefox-based fully portable browser designed to allow anonymous web surfing.

Called Torpark, the browser created by the Hacktivismo organization establishes an encrypted connection to the TOR (The Onion Router) network, which supplies a succession of different IP addresses, reports CNET. Its developers said it differs from other anonymous browsers, such as Anonymizer or SecretSurfer, in that it is free and can be run directly from a USB drive.

Though the browser encrypts data sent to the TOR network, data isn't encrypted between TOR and the destination site, Hacktivismo cautioned; accordingly, user names and passwords should not be used on sites that do not offer a secure login and session, it said.

Testers have reported browser sessions are slower than with an unmodified browser. The official launch of Torpark follows more than a year of development work. Another application, called Torbird, uses the TOR network for email.