Questions tagged [differential-analysis]

Differential cryptanalysis is a form of cryptanalysis which studies cryptographic algorithms by observing how differences in input affect differences on output.

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Why is DES secure against differential cryptanalysis

I was wondering, why DES is secure against Differential Attacks. Some of the S-Boxes have a very bad Differential Uniformity, only one has a DU of 4, 3 have a DU of 6 and the others are much worse. ...
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Symmetric property of DDT of inverse function

Given a bijective function $F: \mathbb{F}_2^n \rightarrow \mathbb{F}_2^n$. The entry of the Difference Distribution Table (DDT) at row $\alpha$ and column $\beta$ is defined as $$DDT_{F}(\alpha,\...
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Implementation of differential cryptanalysis

This question is a little bit more implementation based of differential cryptanalysis. I hope it is okay. I am working with the book "The Block Cipher Companion" on the topic differential ...
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Differential cryptanalysis in “The Block Cipher Companion”

I am practically implementing a differential cryptanalysis on a cipher which can be found in the book "The Block Cipher Companion". Following image shows the cipher: In Fig. 6.10 (page 126) there are ...
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Recover all keys on differential cryptanalysis

I am practically implementing differential cryptanalysis on a cipher from the book "the block cipher companion" . I am successful to get the last key $k_5$. Just to say some words about the ...
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Calculate number of required pairs for differential cryptanalysis

I am currently doing some study on differential cryptanalysis. However, I have two open questions in the field. The first question is: How can I calculate the number of messages necessary for a ...
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good OmegaP for characteristic to use in differential cryptanalysis on DES

how to choose a good OmegaP(input difference) for the characteristic used in differential crypt-analysis on DES?
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Searching for a differential characteristic (differential cryptanalysis)

Currently I am doing some research on differential cryptanalysis. In general I got a good idea about the attack and how it is done. I am currently talking about ciphers with multiple rounds. It ...
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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 cryptanalysis tutorial of Howard M. Heys

I am currently working on some research about differential cryptanalysis. There is a lot of literature about that topic in the internet. One of the most known paper is the tutorial on linear and ...
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differential cryptanalysis on the second round of 4-variant DES

I am using differential cryptanalysis to attack the second key of a 4-variant DES and I am using Shamir and biham book as a reference . they say that we should choose two input Xor P3 and P4 that ...
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Can multiple Pearson permutation tables be reduced or merged?

There was a recent question answered where the accepted solution was a double Pearson hash. It consisted of the following pseudo code:- h = T1[h ^ x[i]] followed ...
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Attacking AES using Round 1 output

I was reading the paper Differential Scan Attack on AES with X-tolerant and X-masked Test Response Compactor and I have a question in the section Differential Scan Attack on AES. What I understand is ...
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Getting the s-box input from its output in differential cryptanalysis on DES

If we try to get K4 using differential cryptanalysis on 4-variant DES, how can we get the input of a certain S-box if we know it's output? This seems hard to do since the substitution operation is ...
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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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Additive differential probability

I am studying about additive differential probability. And I show a paper that is V.Velichkov et al., The Additive Differential Probability of ARX. I have a question in chapter 5.2. V.Velichkov et ...
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Additive Differential of XOR

I'm studying about Additive differential of XOR I saw two papers that are "H.Lipmaa et al., On the Additive Differential Probability of Exclusive-or" and "V.Velichkov et al., The Additive ...
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Differential probability of modular subtraction $xdp^-$

The modular addition has been a main component in block cipher. The use of modular subtraction in block cipher is not common but there are some cipher such as Bel-T cipher which uses both modular ...
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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 $a$ ...
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Minimum number of active s box to be resistance to differential cryptanalysis

I am calculating the minimum number of active s_boxes for block cipher using mixed integer programming, when can we say that block cipher is resistance to differential cryptanalysis after which round? ...
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How does linear vs. non-linear operations relate to cryptographic security and differential cryptanalysis?

I understand what a linear operation is and what a non-linear operation is, but I would like an explanation of specifically how a non-linear operation on input data mitigates differential crytanalysis ...
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Cryptanalysis of MD4 (Wang et al) — how did the authors come up with the collision differential?

Edit: ok, after I re-read the paper a couple of times it is clear that Table 6 is easily derived from Table 5, which describes the collision differential. So the real question is: how did the ...
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The Collision Differential for MD4 - a question on notation (Wang, et al)

In the paper "Cryptanalysis of the Hash Functions MD4 and RIPEMD" the authors introduce the following notation (paragraph 4.1): $\Delta$$H_0$ = 0 $\xrightarrow{(M_,M')}$ $\Delta$$H$ = 0 What exactly ...
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Adding bit constants to the key schedule to reduce rounds?

Bit constants are often added to the key schedule to reduce slide attacks. I have reviewed David Wagner's work, where he showed that the increased rounds in a Feistel network do not help if you have ...
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Compression function cryptanalysis

A compression function converts a fixed-sized input into a smaller fixed size output. Suppose that one has a large collection of input-output pairs for an unknown compression function. We can assume ...
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Calculating the number of rounds required for block cipher with known differential [closed]

Suppose we have a 128-bit block cipher for which the best two-round differential holds with probability $p = 2^7$. Suppose as well that this differential is iterative and that the best differential ...
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it is possible to use quantum algorithm search (Grover's algorithm) for new searching strategies for differential and linear attacks

I am trying to use Grover's algorithm to find Differential characteristic of Feistel and SPN structures block ciphers. basically, which is Finding a good differential characteristic with high ...
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Understanding the wide trail design strategy

I am trying to understand the wide trail design strategy. I have read the paper which describes it from the point of view of AES. From what I understand, it is a technique to increase diffusion in a ...
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Security of the AES with a Secret S-box

In this paper they change the $AES$ S-box to a uniformly random one and answer the questions: How does the security of AES change when the S-box is changed by a secret S-box? Would it be safe to ...
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Does CPA-secure means security against differential cryptanalysis?

I've read on differential cryptanalysis where it traces the differences on the changes of ciphertexts of the same plaintext, except for some bits. However, I wonder is the differential cryptanalysis ...
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Are SHA-2's $\mathit{Maj}$ and $\mathit{Ch}$ functions non-linear?

SHA-2 has two functions: $\mathit{Maj}(x, y, z) = (x \land y) \oplus (y \land z) \oplus (x \land z)$ $\mathit{Ch}(x, y, z) = (x \land y) \lor (\neg x \land z)$ Are these two functions non-linear? ...
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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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Why is variable rotation uncommon in cryptographic primitives?

Most cryptographic primitives I've seen rotate by a constant. RC5 did something different though: For a word size $w=2^n$, you can take the last $n$ bits of a value as a rotation amount. There's more ...
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Minimum difference collision metric

Take a hash function $H$. There will be pairs of messages of the same length $M,M'$ for which $M\ne M',H(M)=H(M')$. Let $P(x)$ be a function counts the number of $1$s in $x$. $d=P(M\oplus M')$, or ...
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If we use another irreducible polynomial for AES how can we show it is still resistant to DCA and LCA?

AES has been rigorously tested against all known attacks. However, I believe there are 30 suitable irreducible polynomials that could be used for AES. If we were to change the current irreducible poly ...
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How can one construct the weakest S-box ever?

Is it possible to come up with an NxN S-box which would have a difference distribution table with N entries of 100% probability? I am studying the properties of S-boxes and I don't quite understand ...
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What is a differential trail?

From what I could find it relates input differences to output differences usually across multiple rounds. But is it the entire probability distribution over all output differences for one input ...
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Differential or Truncated Differential Attack On Small Cipher

The cipher given below is a 16-bit toy cipher which uses 8-bit sbox and 2x2 byte Matrix. The Key $k_0$ and $k_1$ are $\oplus$ with the data. The multiplication with matrix is performed in $GF(2^8)$ ...
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What is an advantage of MDS matrices in block ciphers?

I saw the several articles about MDS matrices. They said that, one goal of MDS matrices is to protect the block ciphers against linear and differential attacks. My question is: For example in the ...
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Signal vs Noise ratio in differential cryptanalysis

What does signal vs noise ratio mean in the context of differential cryptanalysis and how can one use it to derive the number of required plaintext pairs to carry a successful attack ?
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Determining number of required plaintext pairs for differential cryptanalysis

When carrying differential analysis of a SPN network, how can one determine the number of required plaintext for the attack to be successful with high probability?
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Does this approach on MEDP take into account the multiple differential trails?

I was reading this (chapter 3.1) paper, and the author proposed this method to calculate the MEDP on 2-round AES: I cannot fully understand what he is doing but it seems like it iterating over all ...
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What is the meaning of Maximum Expected Differential/Linear Probability (MEDP/MELP)?

I was reading this paper which has a lot of references to the terms MEDP and MELP. Even though i think i got the general meaning, I could not verify that it is indeed correct. For the MEDP, I would ...
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How is the SHA-1 collision detector so fast?

The google collision website shattered.it refers to a collision detector: https://github.com/cr-marcstevens/sha1collisiondetection. It claims a false positive rate of $2^{-90}$ and to take less then ...
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Differential trails in FEAL-8

In this paper the authors describe a differential attack against FEAL-8. They find several short differential trails, then extend the attack to the full 8-Rounds of the cipher by algebraic means. In ...
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In differential cryptanalysis for DES, why is F(0…0) assumed to be always 0…0?

In this paper about differential cryptanalysis, an attack on 2n-Round DES is described. The attack is all about finding certain inputs for DES rounds, for which ...
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What is the difference between strong/weak alignment?

In this answer there is the mention of "weak alignment", followed by an indication that it is related to "resistance to truncated differential cryptanalysis". What exactly is the difference between ...
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Is the difference distribution table of AES S-box uniform?

I am studying about various block ciphers and their weaknesses, so I have a doubt about AES S-boxes, Is the difference distribution table of AES uniform ?
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Can I use a differential that can be traced through the whole cipher with 100% probability?

I'm trying to attack a very simple cipher using differential cryptanalysis as a way of becoming familiar with this method. The cipher is so simple that I've found a differential which I can trace ...
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What is the point of differential cryptanalysis when the amount of necessary plaintext is unrealistic?

As someone with a non-crypto background, I learned that differential cryptanalysis is mostly weak against ciphers like DES because, being a chosen plaintext attack, for a state of art complexity of $2^...