Cryptology ePrint Archive: BibTeX Citation of Report 2011/665

@misc{cryptoeprint:2011:665,
    author = {Jothi Rangasamy \and Douglas Stebila  \and Lakshmi Kuppusamy \and Colin Boyd \and Juan Gonzalez Nieto},
    title = {Efficient Modular Exponentiation-based Puzzles for Denial-of-Service Protection},
    howpublished = {Cryptology ePrint Archive, Report 2011/665},
    year = {2011},
    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.