@misc{cryptoeprint:2009:066,
author = {Jooyoung Lee and Je Hong Park},
title = {Adaptive Preimage Resistance and Permutation-based Hash Functions},
howpublished = {Cryptology ePrint Archive, Report 2009/066},
year = {2009},
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.