@misc{cryptoeprint:2000:042,
author = {Moni Naor and Omer Reingold},
title = {Constructing Pseudo-Random Permutations with a Prescribed Structure},
howpublished = {Cryptology ePrint Archive, Report 2000/042},
year = {2000},
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.