Cryptology ePrint Archive: BibTeX Citation of Report 2015/904

@misc{cryptoeprint:2015:904,
    author = {Junqing Gong and Xiaolei Dong and Zhenfu Cao and Jie Chen},
    title = {Almost-tight Identity Based Encryption against Selective Opening Attack},
    howpublished = {Cryptology ePrint Archive, Report 2015/904},
    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.