Cryptology ePrint Archive: BibTeX Citation of Report 2002/137

@misc{cryptoeprint:2002:137,
    author = {Nicholas J. Hopper and John Langford and Luis von Ahn},
    title = {Provably Secure Steganography},
    howpublished = {Cryptology ePrint Archive, Report 2002/137},
    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.