-----BEGIN PGP SIGNED MESSAGE----- I know Raph already answered this, but I want to toss my few cents in. It is important to understand the threat model of Mixmaster. I assumed that all links and some remailers would be compromised. My goal was to ensure that no information about the message was revealed except to the first and last remailers in the chain. To borrow from physics (black hole) terminology, the message must have no hair. Any active padding by the remailer implies that it knows an upper limit on the size of the actual message. If each remailer removes some information, which must be replaced, then conspiring remailers can obtain information about the where messages are going, by comparing size, and knowing that the "kernel" of the message can only shrink. This last statement is true unless remailers add extra hops, which they encrypt. The reason this is not effective has been thoroughly discussed on this list. Take a look at the essay on my home page. It explains most of the design decisions. -Lance Cottrell At 5:25 PM 4/25/96, Mark M. wrote:

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I was thinking about how Mixmaster needs a separate message format so it can make messages a fixed size and add a packet ID. However, couldn't all this be done with PGP? With PGP, the length of the file being encrypted is encrypted itself, so it would be possible to append random data to the end of the file to make the message a fixed length like Mixmaster. Also, the packet-ID could be implemented by putting a line such as the following in the message:

:: Packet-ID: foobar

The only other thing that would have to be taken care of is chaining. The way I could see this working is to have a header in the encrypted message that tells the remailer whether it should de-armor the message at the next layer, append random data, then re-armor, and pass it to the next remailer. Am I missing something?

- -- Mark

=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-= markm@voicenet.com | finger -l for PGP key 0xf9b22ba5 http://www.voicenet.com/~markm/ | bd24d08e3cbb53472054fa56002258d5 "The concept of normalcy is just a conspiracy of the majority" -me

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-----BEGIN PGP SIGNATURE----- Version: 2.6.2 iQEVAwUBMYFHQfPzr81BVjMVAQH0qgf8DbhHB2rHxYAAMBKoOAiDRW7zy+UViknf 2BmIv6NDW2MYtTHNSLykDVx3XQCeGG4QuuFcmdveD3livQizC9Tb5Rj8cMNI/Qb6 R7RYEAsaraluxBYNxHxFPejZUy/r9jjJm+LzSVaYVfEdzgt5jjNrm2YV53nOinD8 4sfgBtWNKWAyiyl7lTFWKAhLdfYsp3klTecnEBuPetZlv1V3b4RR2xZi4ggIK4VR lFkASSQUp/c+JhkJWRcNw6z+Df2XJ59ORUGC+MuJp/W56YoTGicca3mI64qGwg7J 745XF8oAOuD3OCvreWiOYU/LScG3lKKMYfhCyWnGXpt32BJyM5hm1w== =WD5g -----END PGP SIGNATURE----- ---------------------------------------------------------- Lance Cottrell loki@obscura.com PGP 2.6 key available by finger or server. Mixmaster, the next generation remailer, is now available! http://www.obscura.com/~loki/Welcome.html or FTP to obscura.com "Love is a snowmobile racing across the tundra. Suddenly it flips over, pinning you underneath. At night the ice weasels come." --Nietzsche ----------------------------------------------------------