On the Construction of Highly Nonlinear Permutations

Highly nonlinear permutations play an important role in the design of cryptographic transformations such as block ciphers, hash functions and stream ciphers. The substitution boxes of DES are relatively small in dimension and they can be generated by testing randomly chosen functions for required design criteria. Security may be increased by the use of substitution transformations of higher dimensions. But when the dimensions grow larger, analytic construction methods become necessary.