@misc{cryptoeprint:2008:174,
author = {Somitra Kumar Sanadhya and Palash Sarkar},
title = {Non-Linear Reduced Round Attacks Against SHA-2 Hash family},
howpublished = {Cryptology ePrint Archive, Report 2008/174},
year = {2008},
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.