@misc{cryptoeprint:2015:409,
author = {Jie Chen and Romain Gay and Hoeteck Wee},
title = {Improved Dual System ABE in Prime-Order Groups via Predicate Encodings},
howpublished = {Cryptology ePrint Archive, Report 2015/409},
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.