@misc{cryptoeprint:2009:444,
author = {Zhijun Li and Guang Gong and Zhiguang Qin},
title = {Secure and Efficient HB-CM Entity Authentication Protocol},
howpublished = {Cryptology ePrint Archive, Report 2009/444},
year = {2009},
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.