@misc{cryptoeprint:2015:301,
author = {Yupu Hu and Huiwen Jia},
title = {Cryptanalysis of GGH Map},
howpublished = {Cryptology ePrint Archive, Report 2015/301},
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.