@misc{cryptoeprint:2015:153,
author = {Kai-Min Chung and Jonathan Katz and Hong-Sheng Zhou},
title = {Functional Encryption from (Small) Hardware Tokens},
howpublished = {Cryptology ePrint Archive, Report 2015/153},
year = {2015},
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.