Cryptology ePrint Archive: BibTeX Citation of Report 2015/308

@misc{cryptoeprint:2015:308,
    author = {Patrick McCorry and Siamak F. Shahandashti and Dylan Clarke and Feng Hao},
    title = {Authenticated Key Exchange over Bitcoin},
    howpublished = {Cryptology ePrint Archive, Report 2015/308},
    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.