@misc{cryptoeprint:2006:254,
author = {Ilya Mironov and Lintao Zhang},
title = {Applications of SAT Solvers to Cryptanalysis of Hash Functions},
howpublished = {Cryptology ePrint Archive, Report 2006/254},
year = {2006},
note = {\url{http://eprint.iacr.org/}},
}
You will need the url.sty package (comes with most LaTeX installations) for the last line. Otherwise, remove the \url command.