@misc{cryptoeprint:2015:759,
author = {Alice Pellet-Mary and Damien Stehle},
title = {Cryptanalysis of Gu's ideal multilinear map},
howpublished = {Cryptology ePrint Archive, Report 2015/759},
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.