On blending attacks for mixes with memory

Blending attacks are a general class of traffic-based attacks, exemplified by the (n–1)-attack. Adding memory or pools to mixes mitigates against such attacks, however there are few known quantitative results concerning the effect of pools on blending attacks. In this paper we give a precise analysis of the number of rounds required to perform an (n–1)-attack on the pool mix, timed pool mix, timed dynamic pool mix and the binomial mix.