@misc{cryptoeprint:2004:120,
author = {Bartosz Zoltak},
title = {Security of Symmetric Encryption Schemes with One-Way IND-CNA Key Setup},
howpublished = {Cryptology ePrint Archive, Report 2004/120},
year = {2004},
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.