Cryptology ePrint Archive: BibTeX Citation of Report 2002/018

@misc{cryptoeprint:2002:018,
    author = {Jae Choon Cha and Jung Hee Cheon},
    title = {An Identity-Based Signature from Gap Diffie-Hellman Groups},
    howpublished = {Cryptology ePrint Archive, Report 2002/018},
    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.