Cryptology ePrint Archive: BibTeX Citation of Report 2008/056

@misc{cryptoeprint:2008:056,
    author = {Vladislav Kovtun, Thomas Wollinger},
    title = {Fast explicit formulae for genus 2 hyperelliptic curves using projective coordinates (Updated)},
    howpublished = {Cryptology ePrint Archive, Report 2008/056},
    year = {2008},
    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.