@misc{cryptoeprint:2013:202,
author = {Mohammad Ali Orumiehchiha and Josef Pieprzyk and Ron Steinfeld},
title = {Breaking NLM-MAC Generator},
howpublished = {Cryptology ePrint Archive, Report 2013/202},
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.