Mixmaster anonymous remailer

A Mixmaster remailers (also type II remailer ) is an anonymizing Internet service that accepts e-mail messages and forwards ( remailers ). Here, all the information that suggest the origin and the sender removed before forwarding the message.

The Mixmaster server software handles only encrypted e- mail in a very specific format. Unlike the application of the older Cypher Punk protocol, the sender has to rely on a specialized Mixmaster client software to create such e -mail.

Origin and development

Mixmaster was created after the proposals by Lance Cottrell and should eliminate the weaknesses of the Cypher Punk remailer. The underlying mix -net Protocol even David Chaum has developed in 1981. Today's Mixmaster message format is in use since 1995 on the Internet.

Mixmaster software can be installed on different operating systems. It arose individual client solutions exclusively for Windows or Unix derivatives ( including Linux ); well as those that support the next Mixmaster also Cypher Punk.

Method

Before forwarding a message through the remailer the so-called message header is modified while removing the sender- related information. The final recipient of such treated e-mail will be the only indication of the sender of the remailer.

Techniques that increase the safety level of Cypher remailers later, are from the outset part of the Mixmaster Protocol. Already the Mixmaster client assures that dispatches each message is the same size. These large e- mails are divided into smaller by about 20 KiB, brought smaller by adding random data to this size.

For Mixmaster chaining remailers and encryption are fixed by means of public-key method part of the protocol. Individual message packets, which may arise through the forced division, can have different ( and differently long ) Remailerketten, the last member of each one and the same remailer must be to be delivered. Only the last remailer is able to compose such a message.

Mixmaster can be combined with Cypher Punk remailers and then take over may automatically reformatting a conventional Cypherpunk message in the Mixmaster format ( remix) and forwarding to other mixmaster remailers.

Other features

• The Mixmaster server maintains a news pool in which all incoming messages are not collected. The pool size is adjustable.
• Messages are sent from the message pool at random.
• Takes place within a period not sufficient traffic, Mixmaster itself generates messages without any meaningful content that shipped via remailers, but ultimately destroyed.
• Copies of the same e- mail can be sent via different chains. Mixmaster entertain a message cache destroyed the duplicates after the first successful delivery on the basis of the last remailer; the final recipient receives each mail only once.

Attacks against the Mixmaster remailers

Mixmaster are resistant to almost all known attacks. So far, only a theoretical approach is known:

An attacker keeps the message whose receiver he wants to find out back. It then sends its own message to the Mixmaster. This makes it is until the message pool of Mixmasters filled with its news. He then sends the held message going on. All messages go through the Mixmaster, either be sent to the attacker or to a third address. The third address is the recipient of the retained message.