@misc{cryptoeprint:2014:135,
    author = {Ding Wang, Debiao He, Ping Wang, Chao-Hsien Chu},
    title = {Anonymous Two-Factor Authentication in Distributed  Systems: Certain Goals Are  Beyond Attainment},
    howpublished = {Cryptology ePrint Archive, Report 2014/135},
    year = {2014},
    url = {https://eprint.iacr.org/2014/135},
}