@misc{cryptoeprint:2013:345,
author = {Arnab Roy and Srinivas Vivek},
title = {Analysis and Improvement of the Generic Higher-Order Masking Scheme of FSE 2012},
howpublished = {Cryptology ePrint Archive, Report 2013/345},
year = {2013},
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.