Cryptology ePrint Archive: BibTeX Citation of Report 2007/147

@misc{cryptoeprint:2007:147,
    author = {Vladimir Shpilrain and Gabriel Zapata},
    title = {Using decision problems in  public key cryptography},
    howpublished = {Cryptology ePrint Archive, Report 2007/147},
    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.