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3

All of the mathematical operations within the s-boxes, shift row, and mix column should be known to the attacker, correct? Yes, see Kerckhoff's principle I understand they could be hard to calculate but aren't they static operations for the most part? I'm interpreting "static operations" to mean subBytes + shiftRows + mixColumns + addRoundKey, and that ...


4

The XOR state is irreversible without the proper key which is what I understand, so whats the point of all of the other operations that happen on the key? Suppose all we had was secret keys and the XOR operation. Well, actually, it is possible to build a secure cipher out of that, called the one time pad. One time pads offer perfect secrecy, but suffer ...


2

If you include a key addition layer ($K_1$) at the output as well the key addition layer ($K_0$) at the input of the Sbox then you can perform linear cryptanalysis on this simple cipher. You shall have access to $P,C$ pairs but no keys, of course, and the $P/C$ relationship is $$C=K_1\oplus(S(P\oplus K_0))$$ and so your linear bias equations become something ...


3

Assuming your differential uniformity and non-linearity figures are correct, then yes, your s-box is slightly stronger against basic differential and linear cryptanalysis. Although Anubis already was essentially immune to basic differential and linear cryptanalysis. However your s-box would need to be evaluated against other forms of cryptanalysis (e.g. ...


0

The image below shows the 30 irreducible polynomials for GF2^8. As an interesting factor it seems that 16 out of 30 has Hamming Weight of 4 (ignoring the MSB i.e x^8) and more interestingly 7 out of these 16 (with Hamming Weight 4) has nibble wise balanced Hamming Weight. Twofish m(x) is on of the nibble wise balanced. One more beauty you will find in it ...


6

Coincidentally I had the Twofish and Camellia design papers open on my computer when you asked this question. S-boxes in the ciphers Both are Feistel ciphers, and the way the s-boxes are used is quite different when compared to AES. The s-boxes are used almost identically in Twofish and Camellia, but key mixing and post s-box diffusion are quite different. ...



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