@misc{cryptoeprint:2007:447,
author = {Xianhui Lu, Xuejia Lai, Dake He, Guomin Li},
title = {Weak adaptive chosen ciphertext secure hybrid encryption scheme},
howpublished = {Cryptology ePrint Archive, Report 2007/447},
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.