# Questions tagged [mds]

An MDS matrix (Maximum Distance Separable) is a matrix representing a function with certain diffusion properties that have useful applications in cryptography.

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### Near Maximum Distance Separable Code

I want to find the minimum distance of an $[8,4]$ Near MDS code over a finite field F_4 (NMDS Code is a type of linear code). I want to know which programming language has a built-in function that ...
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### How to check whether function provides full diffusion or not?

In "The Skein Hash Function Family" paper authors wrote: The MIX/permute structure has been designed to provide full diffusion in 9 rounds for Threefish-256, 10 rounds for Threefish-512, ...
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### regarding MDS matrix and security

I found a construction for MDS matrix (algorithm 4 of https://eprint.iacr.org/2020/1143) for a hash function that compresses elements in a prime field $F_p$ If the hash has a rate and capacity $(r,c)$ ...
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### Sage code for finding generator matrix of MDS code

Let $L$ be an $[n,k]$ code. A $k\times n$ matrix $G$ whose rows form a basis for $L$ is called a generator matrix for $L$. A linear $[n,k,d]$ code with largest possible minimum distance is called ...
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### AES MDS D-XOR and S-XOR count

I am trying to implement the D-XOR and S-XOR count in python but despite reading multiple articles on how to perform the calculation I have failed to understand the process used. I would appreciate it ...
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### MDS Matrix Elements

Can zero be one of the elements used in an MDS matrix (in the context of AES)? Based on what I have read all entries of an MDS Matrix need to be non-zero. Also, I would appreciate any help in ...
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### How to find the AES branch number?

By definition, branch number Definition: The branch number of a linear transformation $F$ is $$min_{a\neq0}(W(a) + W(F(a)))$$ Source here (7.3.1) For AES MixColumns $a \in GF(2^8)^4$ since ...
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### How to calculate active s-boxes from branch number?

If MDS in AES has branch number 5 (so 5 active s-boxes in 2 rounds), wouldn't that mean 4 rounds of AES has $5*2=10$ active s-boxes? AES paper says it has 25 ($5^2$?) active s-boxes in 4 rounds. How ...
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### Rijndael S-boxes: Where do the $\mu$ and $\nu$ polynomial ring elements come from?

I've asked some other questions before about Rijndael's S-boxes, and step by step I'm coming to an understanding; but those steps often guide me to new questions. I did some lines of code to ...
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### Variants of AES? [closed]

Would variants of AES provide the same level of security as AES, say by just replacing the S-box with another one, MDS matrix of Mixcolumn, etc.?