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*To*: [email protected]*Subject*: Re: Can someone verify this conjecture for me?*From*: Hal <[email protected]>*Date*: Fri, 6 Jan 1995 20:33:14 -0800*Sender*: [email protected]

-----BEGIN PGP SIGNED MESSAGE----- From: [email protected] (Russell Nelson) > > I'd like to make sure I understand how a digital mix works. I've read > Chaum's paper on it, but hey, there's a reason why I don't have a Phd > in spite of having all the coursework done. > > It seems like it solves two separate problems: 1) foiling traffic > analysis, and 2) foiling a cheater remailer. The problems are > separate, really, because if you really, really trust the remailer (as > many people do Julf), then 2) isn't a problem. All you need to do is > solve 1. Or, you can solve 1) by using a single remailer. A > necessary but not sufficient step to foil traffic analysis is to strip > headers. My take on the paper is that he first presents the "mix", or remailer, as a method of foiling traffic analysis. Then he extends this to the "cascade", or chain of remailers, which does not improve traffic analysis resistence but as you say provides some immunity against a bad operator. > If you trust any one remailer, then you needn't bother using any other > ones (assuming that remailer has enough traffic, delay, mixing, etc to > foil traffic analysis). There's no real difference between using a > set (N>1) of trusted remailers and using only one, because you can > consider the set of remailers to be a single remailer from the point > of view of traffic analysis. There are other differences which may be relevant in practice. One is bandwidth. With a Chaumian cascade of N remailers you get N times the bandwidth used, as well as increased latency through the remailer network. One thing that is not often appreciated in Chaum's paper is that at least in his first description of the cascade, the assumption is that all users use the same sequence of remailers in the same order. We OTOH usually assume a different model, where the different possible paths are chosen with some distribution and randomness. I posted an analysis of some of the impacts of this difference a few months ago. Hal -----BEGIN PGP SIGNATURE----- Version: 2.6 iQBVAwUBLw4ZXhnMLJtOy9MBAQGjtwIA7tlEMnKPqUAVqAMSmK6EE6eaOlzhqeLL hsHXhNJajyZQjF6osybGSYJ00UBhRkbAxUOtjY4MNf6oMrb9fKRxGg== =A3oZ -----END PGP SIGNATURE-----

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