@misc{cryptoeprint:2007:033,
author = {Eike Kiltz},
title = {From Selective-ID to Full Security: The Case of the Inversion-Based Boneh-Boyen IBE Scheme},
howpublished = {Cryptology ePrint Archive, Report 2007/033},
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.