@misc{cryptoeprint:2009:119,
author = {Marcel Medwed},
title = {A Continuous Fault Countermeasure for AES Providing a Constant Error Detection Rate},
howpublished = {Cryptology ePrint Archive, Report 2009/119},
year = {2009},
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.