Cryptology ePrint Archive: BibTeX Citation of Report 2003/129

@misc{cryptoeprint:2003:129,
    author = {Fangguo Zhang and Reihaneh Safavi-Naini and Willy Susilo},
    title = {Attack on Han et al.'s ID-based Confirmer (Undeniable) Signature at ACM-EC'03 },
    howpublished = {Cryptology ePrint Archive, Report 2003/129},
    year = {2003},
    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.