@misc{cryptoeprint:2011:507,
author = {Charanjit Jutla and Arnab Roy},
title = {Relatively-Sound NIZKs and Password-Based Key-Exchange},
howpublished = {Cryptology ePrint Archive, Report 2011/507},
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.