Peer-to-Peer

Chapter 7. Mixmaster Remailers

Adam Langley, Freenet

Remailers are one of the older peer-to-peer technologies, but they have stood the test of time. Work done on them has helped or motivated much of the current work in the P2P field. Furthermore, they can be valuable to users who want to access many of the systems described in other chapters of this book by providing a reasonable degree of anonymity during this access, as explained in Chapter 15.

Anonymous remailers allow people to send mail or post to newsgroups while hiding their identities. There are many reasons why people might want to act anonymously. Maybe they fear for their safety if they are linked to what they post (a concern of the authors of the Federalist Papers), maybe they think people will prejudge what they have to say, or maybe they just prefer to keep their public lives separate from their private lives. Whatever the reason, anonymous posting is quite difficult on the Internet. Every email has, in its headers, a list of every computer it passed through. Armed with that knowledge, an attacker could backtrack an email to you. If, however, you use a good remailer network, you make that task orders of magnitude harder.

Mixmasters (also known as Type 2 remailers) are the most common type of remailer. The Type 1 remailers are technically inferior and no longer used, though Mixmasters provide backward compatibility with them. The first stable, public release of Mixmaster was on May 3, 1995, by Lance Cottrell. The current ...