@misc{cryptoeprint:2005:465,
author = {S.G. Barwick and W.-A. Jackson},
title = {A sequence approach to constructing perfect hash families},
howpublished = {Cryptology ePrint Archive, Report 2005/465},
year = {2005},
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.