@misc{cryptoeprint:2003:016,
author = {Cheng-Kang Chu and Li-Shan Liu and Wen-Guey Tzeng},
title = {A Threshold GQ Signature Scheme},
howpublished = {Cryptology ePrint Archive, Report 2003/016},
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.