@misc{cryptoeprint:2010:440,
author = {Christophe Giraud and Adrian Thillard},
title = {Piret and Quisquater's DFA on AES Revisited},
howpublished = {Cryptology ePrint Archive, Report 2010/440},
year = {2010},
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.