3 Lee, Ruby B. Rivest, R L Robshaw, M J B Shi, Z J Yin, Y L 2004 On Permutation Operations in Cipher Design Proceedings of the International Conference on Information Technology (ITCC 2004) Las Vegas, Nevada, USA 569-577 April 5-7, 2004 http://palms.ee.princeton.edu/PALMSopen/lee04permutation.pdf