Cryptology ePrint Archive: BibTeX Citation of Report 2007/273

@misc{cryptoeprint:2007:273,
    author = {Mihir Bellare and Sarah Shoup},
    title = {Two-Tier Signatures, Strongly Unforgeable Signatures, and Fiat-Shamir without Random Oracles},
    howpublished = {Cryptology ePrint Archive, Report 2007/273},
    year = {2007},
    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.