@misc{cryptoeprint:2003:116,
author = {Xiaofeng Chen and Fangguo Zhang and Kwangjo Kim },
title = {A New ID-based Group Signature Scheme from Bilinear Pairings},
howpublished = {Cryptology ePrint Archive, Report 2003/116},
year = {2003},
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.