@misc{cryptoeprint:2011:649,
    author = {Fanbao Liu and Changxiang Shen and Tao Xie and Dengguo Feng},
    title = {On the Security of NMAC and Its Variants},
    howpublished = {Cryptology ePrint Archive, Report 2011/649},
    year = {2011},
    url = {http://eprint.iacr.org/2011/649},
}