@misc{cryptoeprint:2007:266,
author = {Wei Han and Dong Zheng and Ke-fei Chen},
title = {Filling the Gap between Voters and Cryptography in e-Voting},
howpublished = {Cryptology ePrint Archive, Report 2007/266},
year = {2007},
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.