48th Annual IEEE Symposium on Foundations of Computer Science (FOCS'07)
Near Optimal Bounds for Collision in Pollard Rho for Discrete Log
Providence, Rhode Island
October 21-October 23
ISBN: 0-7695-3010-9
We analyze a fairly standard idealization of Pollard?s Rho algorithm for finding the discrete logarithm in a cyclic group G. It is found that, with high probability, a collision occurs in {\rm O}(\sqrt {\left| G \right|\log \left| G \right|\log \log \left| G \right|} ) steps, not far from the widely conjectured value of \Theta (\sqrt {\left| G \right|} ). This improves upon a recent result of Miller-Venkatesan which showed an upper bound of {\rm O}(\sqrt {\left| G \right|} \log ^3 \left| G \right|). Our proof is based on analyzing an appropriate nonreversible, non-lazy random walk on a discrete cycle of (odd) length \left| G \right|, and showing that the mixing time of the corresponding walk is {\rm O}(\log \left| G \right|\log \log \left| G \right|).
Citation:
Jeong Han Kim, Ravi Montenegro, Prasad Tetali, "Near Optimal Bounds for Collision in Pollard Rho for Discrete Log," focs, pp.215-223, 48th Annual IEEE Symposium on Foundations of Computer Science (FOCS'07), 2007