@misc{cryptoeprint:2011:348,
author = {Marcel Medwed and Francois-Xavier Standaert},
title = {Extractors Against Side-Channel Attacks: Weak or Strong?},
howpublished = {Cryptology ePrint Archive, Report 2011/348},
year = {2011},
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.