@misc{cryptoeprint:2002:091,
author = {Jovan Dj. Goli\'{c}},
title = {Multiplicative Masking and Power Analysis of AES},
howpublished = {Cryptology ePrint Archive, Report 2002/091},
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.