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From: Louis Cypher (alt.anonymous.messages)
Define "f" as the fraction of remailer using population sending a message in a given tick. This is also the probability that any individual will send a message in a given tick. The probability of a given pair of corespondents in a given tick is f^2 The probability of a pair of corespondents occurring m times in n ticks is m p= 1 - Sum [(f^2)^i (1 - f^2)^(n-i) n! / (i! (n-i)!)] i=0
Hmm... this sounds very similar to the results of my analysis which I posted yesterday (Subject: analysis of Chaum's MIX continued), which I think is slightly more general.
Lets put some numbers in there.... [deleted] So, for a remailer using population of 10,000 you had better send less than 5 messages per month to your accomplice. This only gets worse the longer you keep it up. You can not send 4 per month, month after month.
Plugging these numbers into my formula, the "threshold of tracibility" comes out to be 4 messages. This is probably due to the fact that I used a normal approximation for the binomial probability (the p in the above formula). The general conclusion however is the same: unless most users send a lot of dummy mail to each other, a Chaum type mix will not provide very good untracibility. The other possible way to increase untracibility is to decrease the number of batches per unit time (i.e., increase average latency). This implies that with a Chaumian mix, there is an unavoidable tradeoff between untracibility, bandwidth (i.e., how much dummy mail has to be sent), and latency. Wei Dai -----BEGIN PGP SIGNATURE----- Version: 2.6.2 iQCVAwUBLybywzl0sXKgdnV5AQF0+AP/e5sKTVt5plvGydmILm+cBF14q6IJttDJ U0Es21jMH0hYPreiRwfUXwMc+bLs/RfTdmGBr0KUPHow0khlzfGHjU8ZKOMknSI/ +qvqHlMRPDfvKnp244qsQUJ1UmLAezeNObO4OMbejWbRRGu+Dd1iEeBpgnFOh0bH 6grf4VupdpU= =+Um1 -----END PGP SIGNATURE-----