Cryptology ePrint Archive: BibTeX Citation of Report 2002/139

@misc{cryptoeprint:2002:139,
    author = {Maria Isabel Gonzalez Vasco and Rainer Steinwandt },
    title = {Reaction Attacks on Public Key Cryptosystems Based on the Word Problem },
    howpublished = {Cryptology ePrint Archive, Report 2002/139},
    year = {2002},
    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.