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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170 views

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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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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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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162 views

Differential bound of the S-Box in GOST R34.11-2012

In Russian GOST R34.11-2012 LPS-transformation is used. LPS gets all of its non-linearity from the 8-bit S-box S, which apparently has been designed to offer resistance against classical methods of ...
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76 views

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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Is TripleDES 168bit vulnerable to Differential Cryptanalysis?

I was reading this paper. In the table-1 of the paper it says TripleDES (showing both 128bit and 168bit keysize) is vulnerable to Differential Cryptanalysis. It also says that AES (showing all three ...
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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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1answer
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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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573 views

S-box with differential uniformity = 2

I read that we do not know if there exists an 8x8 sbox with differential uniformity = 2. I suppose we cannot compute every possible sbox because there are $64!$ possible s-boxes. Am I right?
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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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1answer
230 views

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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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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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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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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1answer
128 views

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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139 views

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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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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1answer
65 views

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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1answer
43 views

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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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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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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DES with the bitwise complement of a key

I was reading upon Biham and Shamir's paper and a fact has been presented over there: if $ P_1 = \bar P_2$ and I choose a key $K_1 = \bar K_2$ then in that case $$T_1 = DES(P_1, K_1)$$ $$T_2 = DES(...
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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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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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162 views

Countering Cryptographic Attacks

By reading Camellia Design and Analysis document following is my understanding about few cryptographic attacks from designer point of view. Differential and Linear Crypt-analysis. Number of Active S-...
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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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Why is the permutation in AES (and other ciphers) not random or key-dependent?

If the permutation in AES (or other ciphers) were randomly generated or dependent on the key, would it not be stronger against differential attacks? If this is so, then might we need fewer rounds for ...
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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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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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255 views

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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125 views

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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578 views

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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How to build a difference distribution table?

i am studying about differential cryptanalysis, and found one metric to measure the resistance of a sbox to it, but to use it, it is necessary to build a difference distribution table, like the one in ...
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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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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 ...