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Hot answers tagged s-boxes

Generate ANF from SBox

This is useful to know in general. Given the Sbox map, generate the truth tables for the bits of the map. From the truth tables, obtain the algebraic normal form, via the Mobius transform. So, given ...
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Why don't table lookups run in constant time?

It mostly has to do with the real world influence of memory caches. A cache is a small amount of fast memory; when you read from memory, the contents are placed in this fast memory (possibly along ...
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AES s-box representation

The tricky point is that $\mathbb{F}_2^8$ is not a field; it is a degree-8 vector space. Multiplications are not defined on vector spaces. However, the $A$ transform is defined only on the vector ...
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S-box basic question

Good question and yes, it would appear that data is lost. And technically, something clearly must disappear as 6 don't go into 4. But consider the overall architecture of DES: Trace the flow of the ...
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Desirable S-box properties

Desirable Properties For simplicity, I’m skipping some of the details here… but the main criteria of a good s-box are: miul It should have balanced component functions, The non-linearity of its ...
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Why is the DES s-box non-linear? Why does it make the cracking of the cipher more difficult?

It is of course possible to write DES or any block cipher as a system of non-linear equations involving the plaintext bits, the ciphertext bits, and the key bits, which hold with probability 1. In ...
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AES with linear S-Box

does the cipher become entirely affine and hence trivially weak? Yes; the AES sbox is the only source of nonlinearity (the ShiftRows and MixColumns are linear, and AddRoundKeys for a fixed key is ...
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What's happens if we use the weakest S-BOX for AES?

See: How can one construct the weakest S-box ever? and How do I choose the best 3*3 s-boxes? I believe that user Hend's question is not "how to design the worst possible S-box" but about "having ...
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