Cryptology ePrint Archive: BibTeX Citation of Report 2009/100

@misc{cryptoeprint:2009:100,
    author = {Gaetan Bisson and Andrew V. Sutherland},
    title = {Computing the endomorphism ring of an ordinary elliptic curve over a finite field},
    howpublished = {Cryptology ePrint Archive, Report 2009/100},
    year = {2009},
    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.