@misc{cryptoeprint:2010:160,
author = {Shengbao Wu and Mingsheng Wang and Zheng Yuan},
title = {A Flaw in The Internal State Recovery Attack on ALPHA-MAC},
howpublished = {Cryptology ePrint Archive, Report 2010/160},
year = {2010},
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.