@misc{cryptoeprint:2011:095,
author = {Orr Dunkelman and Nathan Keller and Adi Shamir},
title = {ALRED Blues: New Attacks on AES-Based MAC's},
howpublished = {Cryptology ePrint Archive, Report 2011/095},
year = {2011},
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.