@misc{cryptoeprint:2011:166,
author = {Jeremy Clark and Urs Hengartner},
title = {Selections: Internet Voting with Over-the-Shoulder Coercion-Resistance},
howpublished = {Cryptology ePrint Archive, Report 2011/166},
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.