Just read this paper published in PET02 "Towards an Information Theoretic Metric for Anonymity" [1]: http://www.cl.cam.ac.uk/~gd216/set.pdf or http://www.cl.cam.ac.uk/~gd216/set.ps it uses a Shannon like entropy model for the anonymity provided by a system uses this model to analyse the effect of different parameters one can tune with mixmaster (POOLSIZE, RATE, in mixmaster.conf). The "anonymity entropy" measurement can be interpreted as how many bits of information the attacker needs to identify a user and is computed from probabilities. Would be interesting to try estimate the entropy provided by the current mixmaster network. A number of nodes publish their parameter choices, and traffic volume over time (in hourly increments). Adam -- http://www.cypherspace.org/adam/ [1] @inproceedings{Serjantov:02:info-theoretic-anon, author = "Andrei Serjantov and George Danezis", title = "Towards an Information Theoretic Metric for Anonymity", booktitle = "Proceedings of the Workshop on Privacy Enhancing Technologies", year = "2002", note = "Also available as \url{http://www.cl.cam.ac.uk/~aas23/papers_aas/set.ps}" }