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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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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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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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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(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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45 views

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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43 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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33 views

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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45 views

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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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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135 views

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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228 views

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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16 views

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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51 views

Are the weaknesses of my functions attackable?

I got specific problem with my functions in $128$-bit block cipher. One round of encryption is like that: $input$ $\rightarrow$ $F(k_{i},input)$ $\rightarrow$ reverse block $\rightarrow$ $F(k_{i+1},...
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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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46 views

Guess the number of characteristics in differential cryptanalysis

I am doing some research on differential cryptanalysis for my master thesis. I analyzed some toy ciphers like the one in the popular tutorial about differential and linear cryptanalysis from heys Link....
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144 views

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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74 views

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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44 views

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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43 views

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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21 views

Non-linear phase that's Side channel attack proof

I'm designing a cipher and I'm looking for a Non-linear phase in my cipher that is side channel attack proof, I know that Sboxes are vulnerable to to that because of accessing the cache. I'm thinking ...
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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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38 views

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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34 views

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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36 views

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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27 views

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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39 views

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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53 views

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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124 views

Differential cryptanalysis filtering process

This question is a little more implementation based. I am writing my masters thesis on differential cryptanalysis and I wrote a program to evaluate some things about differential cryptanalysis. I ...
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128 views

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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109 views

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?