@misc{cryptoeprint:2006:025,
author = {Denis Charles and Kamal Jain and Kristin Lauter},
title = {Signatures for Network Coding},
howpublished = {Cryptology ePrint Archive, Report 2006/025},
year = {2006},
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.