@misc{cryptoeprint:2006:072,
author = {Yaniv Shaked and Avishai Wool},
title = {Cryptanalysis of the Bluetooth E0 Cipher using OBDD's},
howpublished = {Cryptology ePrint Archive, Report 2006/072},
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.