Cryptology ePrint Archive: BibTeX Citation of Report 2013/120

@misc{cryptoeprint:2013:120,
    author = {Gergely Alpár and Jaap-Henk Hoepman and Wouter Lueks},
    title = {An Attack Against Fixed Value Discrete Logarithm Representations},
    howpublished = {Cryptology ePrint Archive, Report 2013/120},
    year = {2013},
    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.