@misc{cryptoeprint:2012:645,
    author = {Eduarda S. V. Freire,  Kenneth G. Paterson, Bertram Poettering},
    title = {Simple, Efficient and Strongly KI-Secure Hierarchical Key Assignment Schemes},
    howpublished = {Cryptology ePrint Archive, Report 2012/645},
    year = {2012},
    url = {http://eprint.iacr.org/2012/645},
}