# 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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### Biasedness of the XOR variable of two independent biased boolean variable

My question is very basic one. Suppose there are two independent boolean variable $X_1$ and $X_2$. It is given that $X_1$ is biased towards $0$ and $X_2$ is biased towards $1$ with same amount of bias....
136 views

### Linear approximation table of AES S-Box

I am trying to create linear approximation table of AES SBox to better understand linear cryptanalysis, I have followed the formula in this paper (page 7 of pdf file) to be able to generate the linear ...
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### Threshold of resistance against Linear Cryptanalysis

In the AES proposal, the last sentence on page 30 it is said: To be resistant against LC, it is a necessary condition that there are no linear trails with a correlation coefficient higher than 2^(n/2)...
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### Is the linear and differential cryptanalysis only dependent on Sbox?

While performing the linear and differential cryptanalysis a Linear Approximation Table(LAT) and a Different Distribution Table(DDT) is required which is created exploiting the S-box of the cipher ...
260 views

### Understanding Linear Cryptanalysis

I'm reading about the linear cryptanalysis of an SPN and I have some questions about the practicality of this. The example I'm looking at is from 3.3.3 of Stinson's Book and I believe the same example ...
47 views

### Linear approximattion of $(x+y) \bmod 2^n$ in FSM of SNOW 2.0 where $x,y$ in $F_{2}^n$

I would like to understand the linear approximation of $(x+y) \bmod 2^n$ by linear masking method in the paper refereed ""Improved Linear Distinguis'hers for SNOW 2.0" by Kaisa Nyberg and Johan Wall´...
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### Correlation of an approximation over a random permutation

I read a paper of linear cryptanalysis that is J.Daemen et al's Probability distribution of correlation and differentials in block cipher. In this paper's lemma 8's proof, I can't understand this ...
1 vote
58 views

### Relation between the correlation coefficients $\widehat F(w) = C(f(a), w^ta)$ and $(-1)^{f(a)}$

In the paper Correlation Matrices by Joan Daemen et. al., the authors state (on page 3) that if the correlation coefficients $C(f(a),w^ta)$ of a Boolean function $f$ are denoted by $\widehat F(w)$ ...
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### Matsui's Linear Cryptanalysis Lemma 1

In Matsui's paper (Linear Cryptanalysis Method for DES cipher), lemma 1. $NS(a, b)$ is even if $a=1,32$,or $33$, then $NS(a,b)=32$ for all $b$ He said that the following lemma is now trivial from ...
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### Stream cipher example for an introductory cryptography course

I am looking for an easily defined stream cipher to illustrate two basic principles in an undergraduate cryptography course: not every bit of the internal state should be used in the keystream; ...
1 vote
163 views

### Matsui's paper on Linear Cryptanalysis of DES

I am trying to derive the best linear approximation for one round DES. I read the question and answer Regarding matsui's Paper on Linear Cryptanalysis of DES several times but still could ...
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### Selection of rotation constants in ARX design

My question is about choosing the rotation values in ARX design such as SIMON-like or SPECK-like ciphers to provide optimal differential and linear immunity. According to this, the selection of $a$ ...