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What is benefit of using substitution before permutation or permutation before substitution in a block cipher?

cn flag

I am trying to understand the difference between the usage of permutation and substitution in a SP Network. Normally, in ciphers except DES, substitution appears to be done before permutation. But what if permutation is done first before the substitution. What are the plausible advantages or disadvantages to these approaches specifically in the SP Network design?

kelalaka avatar
in flag
Just look at the first and last rounds and see the difference....
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