@misc{cryptoeprint:2006:129,
author = {Wei Han and Dong Zheng and Ke-fei Chen},
title = {Some Remarks on the TKIP Key Mixing Function of IEEE 802.11i},
howpublished = {Cryptology ePrint Archive, Report 2006/129},
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.