# Questions tagged [differential-analysis]

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

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### How Differential Cryptanalysis of DES work?

I have been studying the DC of DES. As a beginner, I completed the general structure of DES and began DC. I understand the idea of attack, how to find different characteristics for differential ...
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### Sensitivy Maximization RAPPOR (Local Differential Privacy)

Hi I have a doubt at the end of the proof of the RAPPOR Algorithm, when they say the sensitivity is maximized when $b'_{h+1}=b'_{h+2}=...=b'_{2h}=1$ and $b'_{1}=b'_{2}=...=b'_{h}=0$. I don't ...
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### Targeting integer number of right pair in differential attacks

As we know, purpose of attackers is finding some high probable differential characteristics in differential cryptanalysis. Then they construct some plaintext structures, plaintext pool and expect some ...
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### Backdoor Designer Key Recovery in LowMC-M

The paper https://eprint.iacr.org/2020/986.pdf proposed a framework for embedding a malicious backdoor in LowMC cipher, that will later help the designer to recover the secret key in the known-...
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### I cannot get the meaning of “check s-box”

In second lecture of cryptography, we had a lecture "Block cyphers" and teacher gave me permuted array of numbers 1...10 and letters "a"..."f" and asked me to find XOR ...
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### Building a 4-bit S-box with a 4-uniform DDT

I am looking for a 4-bit S-box which has only 4s in its difference distribution table (except the top left corner) but I was not able to find one in the literature. Has such an S-box been already ...
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### Differential attack on repeating pairs of zeros in blocks

Let's consider $5$ types of vulnerabilities in one round of encryption in 128-bit cipher. We got 00 at the beginning of the block (the first two bits are two zeros). We got 00 in the middle of the ...
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### DFA on aes Giraud's attack on 10 th round

I am trying to implement an attack on aes using Giraud's attack on the last round of aes using a fault injection of one bytes here is the situation normal byte in the 10th position (1,2) of the 4x4 ...
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### Trying to attack specific encryption scheme

Let's consider 128-bit cipher. Now let's consider example keys $k_1$ to $k_{128}$: $k_1$: 10 $k_2$: 1100 $k_3$: 11110000 ... In general every key $k_n$ can be some binary number which is consist of $n$...
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### calculating the branch number/ active bundles of a cipher

I have read the papers Wide Trail Strategy and Wide Trail Design Strategy for Binary MixColumns. These papers describe the need for a good linear transformation in a cipher, a provable mechanism to ...
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### Differenital and linear attack on specific vulnerabilities

Consider 128-bit cipher. It has one weakness. In every round you can find such even number $E$ which is encrypted into block that has $0$ as one of $1-128$ bits (lets say it has $0$ as $k$-th bit). ...
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### Differential and Linear Cryptanalysis on Random Sbox

Assume that we use the key to perform a uniform permutation to generate a sbox. The literature is rich supporting the statement that a random Sbox can make any cryptographic scheme weaker. I have ...
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### Best differential attack on round functions with specific vulnerabilities

I got problem with my encryption functions. They have a repeating series of ones and zeros. It is 128-bit symmetric cipher. Let's consider numbers divisible by $2.$ Let's count how many times are they ...
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### Differential-linear attack on DES

Is there any known differential-linear attack on full round DES? I couldn't found any and couldn't work on this due to time restriction.
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### (Enhancing Linear-Differential Cryptanalysis - Biham et al.) Diff-Lin Extension Characteristic and Characteristic Probability

I studied Langford and Hellman's Differential-Linear Cryptanalysis and moved on to Biham, Dunkelman and Keller's Enhancing Linear-Differential Cryptanalysis. In the paper, although I've read many ...
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### Improving differential cryptanalysis of a vulnerable cipher

How to avoid differential cryptanalysis attacks when you are inventing new cipher? Let's say you have a $16$-round $128$-bit cipher vulnerable on differential cryptanalysis attacks. Now let's say you ...
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### Are these two methods of differential cryptanalysis different?

I'm trying to understand how differential analysis works. I'm reading this and this tutorials, but it looks like they do different things. In the first paper author tells us to bruteforce last round ...
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### Differential analysis for dummies, how key position impact on tactic? [closed]

Im new to cryptoanalysis and started reading A Tutorial on Linear and Differential Cryptanalysis. The author is trying to explain it as simple as he can. But I still got some questions, can anybody ...
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### Is this permutation secure?

Let vector ${\bf d} \in \{ \pm 1 \}^n$ be the message we want to send. In my system, ${\bf d}$ is multiplied by an $n \times n$ Fourier matrix ${\bf F}$, as follows $${\bf x} = {\bf F} {\bf d}$$ ...
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### Check linear and differential cryptanalysis of a new block cipher [duplicate]

I am developing a new block cipher primitive. I would like to test its robustness against attacks of linear and differential cryptanalysis. Is there a tool to evaluate this using only plaintext and ...
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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 ...
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### Whats the probability a random cipher has a high probability differential?

This is a bit vauge and long winded. Any partial answers or comments/ways to make this more precise would be greatly appreciated. Fix some general structure for a cipher, for example Sbox then ...
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### Could a private key recovery via modulus fault attacks be optimised by being able to choose the faulty moduli?

The paper 'Why One Should Also Secure RSA Public Key Elements' describes an attack where an adversary can fully recover a private key by injecting faults into the modulus before exponentiation takes ...
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### Markov ciphers - generalized group operation

I’m reading this paper of Lai and Massey where they give a very nice perspective on differential attacks in general http://www.isiweb.ee.ethz.ch/papers/arch/xlai-mass-inspec-1991-3.pdf They do their ...
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### 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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### AES difference propagation

when does active S box count reduce in AES difference propagation? what is the relationship between active S-boxes and MixColumns? can you please explain it with an example?
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### Definition Problem for toy SPN

I am reading Differential Attack from Stinson-Cryptography: Theory and Practice on a toy example of S-box(block Cipher) with Nr=n=m=4. I am mainly confused in the following definition Definition ...
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### Unknown bit in the output of encryption of data using SIMECK32 cipher?

How is the unknown bits (annotated by red arrow in figure below) come in the OUTPUT after round 1 and round 2 ? Following is the pictorial representation of SIMECK round function operation. Ref: ...
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### what if the S-boxes in DES were “optimal”

if we assume that the s-boxes in DES were optimal. that is for each s-box, every cell in the DDT equals to 4. is there a differential characteristic in a good probability?
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### Why isn't there a final permutation on SPN-based ciphers?

I am doing some research on differential cryptanalysis. Most people who are familiar with that cryptanalysis technique do know the tutorial from Heys (Heys Tutorial). I came currently to the question, ...
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### AES - Non-linearity hinders differential cryptoanalysis

Can you explain me, in simple terms if possible (I'm not a mathematician :( ), why the non-linearity introduced by the AES s-boxes hinder the differential cryptoanalysis ?
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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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### 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 ...
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 ...