@misc{cryptoeprint:2015:979,
author = {Raluca Ada Popa and Nickolai Zeldovich and Hari Balakrishnan},
title = {Guidelines for Using the CryptDB System Securely},
howpublished = {Cryptology ePrint Archive, Report 2015/979},
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.