| 摘要 |
Method and apparatus for nonlinearizing modulo 2 addition (24) based encryption by block substitution techniques which allows use of the substitution scheme with relatively simple hardware and yet makes cryptanalysis more difficult. The basic block substitution (22), a one to one mapping of n bit binary numbers onto themselves, is based on the fact that certain permutations of the n bit binary numbers define a block substitution by modulo 2 addition (24) of one permuted set of numbers to another, and that a subset of these define equations having an additive relationship when viewed as vectors. This allows the simple changing of the transformation on a frequent basis. Then the equations ace nonlinearized, also in an orderly (34) and readily variable manner, so that the remainder of the set equations may no longer be generated from a limited subset of the equations. Various properties of the transformations and methods of using the same are disclosed.
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