Cryptology ePrint Archive: BibTeX Citation of Report 2008/539

@misc{cryptoeprint:2008:539,
    author = {Jan Camenisch and Markulf Kohlweiss and Claudio Soriente},
    title = {An Accumulator Based on Bilinear Maps and Efficient Revocation for Anonymous Credentials},
    howpublished = {Cryptology ePrint Archive, Report 2008/539},
    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.