@misc{cryptoeprint:2005:107,
author = {Ophir Levy and Avishai Wool},
title = {A Uniform Framework for Cryptanalysis of the Bluetooth $E_0$ Cipher},
howpublished = {Cryptology ePrint Archive, Report 2005/107},
year = {2005},
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.