Cryptology ePrint Archive: BibTeX Citation of Report 2015/250

@misc{cryptoeprint:2015:250,
    author = {Junji Shikata},
    title = {Design and Analysis of Information-Theoretically Secure Authentication Codes with Non-Uniformly Random Keys},
    howpublished = {Cryptology ePrint Archive, Report 2015/250},
    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.