| 摘要 |
A method to generate sequences or sub-keys based on a main key, in which each sub-key gives no information to recover the main key or any other sub-keys. The method generates a sub-key based on a main key, comprising the following steps: obtaining a first value by applying to the main key a linear diversification layer by mixing the main key with a constant, applying to the first value a non-linear transformation, this transformation comprising: obtaining a second value by applying the first value to a substitution layer, the substitution layer comprising at least one substitution box (sbox), each substitution box containing at least one table of constants for which the first value serves as the pointer and a pointed constant serves as an output, obtaining a third value by using a diffusion box of multi-permutation type based on the second value, dividing the third value in N blocks of same size, obtaining an output fourth value formed by N blocks, each block of the fourth value being the result of the combination of at least two blocks of the third value, a block having a same index being always omitted, obtaining a seventh value by applying to the fourth value a substitution layer (sigma), obtaining the sub-key by applying to the seventh value of a symmetrical encryption module, the first value serving as a key input for this module.
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