@misc{cryptoeprint:2002:068,
author = {Scott Fluhrer},
title = {Improved key recovery of level 1 of the Bluetooth Encryption System},
howpublished = {Cryptology ePrint Archive, Report 2002/068},
year = {2002},
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.