@misc{cryptoeprint:2007:178,
author = {Dakshi Agrawal and Charanjit Jutla},
title = {Utility Sampling for Trust Metrics in PKI},
howpublished = {Cryptology ePrint Archive, Report 2007/178},
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.