@misc{cryptoeprint:2011:255,
    author = {Sascha Müller and Stefan Katzenbeisser},
    title = {Hiding the Policy in Cryptographic Access Control},
    howpublished = {Cryptology ePrint Archive, Report 2011/255},
    year = {2011},
    url = {http://eprint.iacr.org/2011/255},
}