@misc{cryptoeprint:2002:045,
author = {Dr. K. S. Ooi, Brain Chin Vito},
title = {Cryptanalysis of S-DES},
howpublished = {Cryptology ePrint Archive, Report 2002/045},
year = {2002},
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.