Cryptology ePrint Archive: BibTeX Citation of Report 2008/231

@misc{cryptoeprint:2008:231,
    author = {Jose Carrijo and Rafael Tonicelli and Hideki Imai and Anderson C. A. Nascimento},
    title = {A Novel Probabilistic Passive Attack on the Protocols HB and HB+},
    howpublished = {Cryptology ePrint Archive, Report 2008/231},
    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.