@misc{cryptoeprint:2013:424,
author = {Mihir Bellare and Viet Tung Hoang and Sriram Keelveedhi},
title = {Instantiating Random Oracles via UCEs},
howpublished = {Cryptology ePrint Archive, Report 2013/424},
year = {2013},
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.