@misc{cryptoeprint:2012:116,
author = {Ralf Kuesters and Tomasz Truderung and Andreas Vogt},
title = {Clash Attacks on the Verifiability of E-Voting Systems},
howpublished = {Cryptology ePrint Archive, Report 2012/116},
year = {2012},
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.