Cryptology ePrint Archive: BibTeX Citation of Report 2005/188

@misc{cryptoeprint:2005:188,
    author = {Victor K. Wei and Tsz Hon Yuen and Fangguo Zhang},
    title = {Group Signature where Group Manager, Members and Open Authority are Identity-Based},
    howpublished = {Cryptology ePrint Archive, Report 2005/188},
    year = {2005},
    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.