@misc{cryptoeprint:2004:234,
    author = {Zuo-Wen Tan and Zhuo-Jun Liu},
    title = {On the security of some nonrepudiable threshold proxy signature schemes with known signers},
    howpublished = {Cryptology ePrint Archive, Report 2004/234},
    year = {2004},
    url = {http://eprint.iacr.org/2004/234},
}