# Questions tagged [linear-cryptanalysis]

Linear cryptanalysis is a known plaintext attack and uses a linear approximation to describe the behavior of the block cipher. Given sufficient pairs of plaintext and corresponding ciphertext, bits of information about the key can be obtained and increased amounts of data will usually give a higher probability of success.

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### LAT of sboxes, sum of coloms and rows

let we have sbox s: Vn -> Vn. If we make LAT table for s, fix any row and get a sum by columns, that sum would be $+-2^{n-1}$. And vice versa, if we fix any column and get a sum by rows, that sum ...
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### ¿Can it be proved that both AES's ShiftRows and MixColumns are linear transformation? (if we leave out subBytes and key addition)

I've been researching a bit and found that the mixColumns step could be expressed as matrix multiplication like this: But I'm not sure what's the mathematical proof for it and I can't find an example ...
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### Checking Independence of combination of uniform random variables to use pilling up lemma

My question is very basic one. Suppose $a_0, a_1, a_2, a_3, a_4, b_0, b_1, b_2, b_3, b_4$ are $10$ uniform random variables from $\{0,1\}$ independent of each other. Now there are expressions of the ...
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### Problems with Matsui's Linear Cryptanalysis on round reduced DES

I'm trying to understand the known plaintext attack that is briefly explained in the paper Linear Cryptanalysis Method for DES Cipher by Mitsuru Matsui. I've almost understood it (since I'm ...
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### Linear cryptanalysis of FEAL-4

I am trying to find the sub keys of a FEAL-4 cipher. I am able to get a number of possibilities for $K_0$ after using Michael Stamps formula using a as a constant and going through $2^{32}$ keys. The ...
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### Enhancing Differential-Linear Cryptanalysis

I'm studying Differential-Linear Cryptanalysis, and I'm trying to understand the context from the article Enhancing Differential-Linear Cryptanalysis by Eli Biham et al. There are some difficult ...
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### In DES : Matsui's notation(LC) vs Biham's notation(DC)

I'm doing linear attack for 8 rounds DES. And I just wondering about the difference between Matsui's notation and Biham's notation. In Matsui's paper, numbers bits from 0 to 63 from right to left. In ...
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### Is the following s-box more linear or more non-linear?

I am trying to figure out whether the following simple s-box configuration I created is more linear than non-linear or vice versa more non-linear than linear? The parameters for this 16*4 table of ...
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### What does it mean : "Canonical representative of Sbox is 0123468A5BCF79DE"? and How can we calculate this representative for Sbox?

In paper :Cryptographic Analysis of All 4 × 4-Bit S-Boxes Saarinen has classified $4 \times 4$ S-Boxes and defined Canonical representative for each class of S-Boxes. What does "Canonical ...
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### Differential and Linear trail propagation in Noekeon

In the Noekeon Cipher Specification they write the following : The propagation through Lambda is denoted by $(a \rightarrow A)$, also called a step. Because of the linearity of Lambda it is fully ...
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### Finding maximal $n$-affine subset

We obtained $l$ vectors $B_i$ of $c$ bits $b_{i,j}$. These are an altered form of vectors $A_i$ where the last $n$ bits of each $A_i$ are an affine function of the other bits of that $A_i$. We want ...
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### Security of an S-box based on modular multplicative inverse

The construction of Rijndael's S-box starts with the multiplicative inverses of each number over a finite field. It seems like this is the main source of its non-linearity. I figured that modular ...
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### How can I identify the linear equations for a block cipher with 4 different s-boxes?

For a block cipher with 4 different s-boxes (each used in an individual round) how can I identify the linear equations? Normally, for ciphers like AES with a single s-box, linear cryptanalysis can be ...