Cryptology ePrint Archive: BibTeX Citation of Report 2004/136

@misc{cryptoeprint:2004:136,
    author = {Vipul Goyal and Virendra Kumar and Mayank Singh and Ajith Abraham and Sugata Sanyal},
    title = {CompChall: Addressing Password Guessing Attacks},
    howpublished = {Cryptology ePrint Archive, Report 2004/136},
    year = {2004},
    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.