@misc{cryptoeprint:2004:109,
    author = {Robert Bradshaw and Jason Holt and Kent Seamons},
    title = {Concealing Complex Policies with Hidden Credentials},
    howpublished = {Cryptology ePrint Archive, Report 2004/109},
    year = {2004},
    url = {http://eprint.iacr.org/2004/109},
}