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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Midori block cipher design: importance of $S_b$ as the S-box

With a use of almost MDS the Midori cipher provides a good diffusion. But why $S_b$ is used as S-box and what is its actual importance?
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How to estimate the bias of linear cryptanalysis given the input and output masks

Assume the input linear mask is $a$, and output mask is $b$,for a block cipher $F$ with $r$ round,How to accurately and quickly estimate the bias of linear cryptanalysis? which is \begin{equation*} ...
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Why does differential cryptanalysis always start from the last round?

Suppose we are working with a cipher with the same general structure as AES. I want to attack the cipher in the following way: suppose that the differential holds only for the first round (much higher ...
4 votes
1 answer
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Where did the number of initial plaintexts required for impossible cryptanalysis on Mini-AES came from?

I'm implementing impossible differential cryptanalysis on AES and I've started with implementing it on mini-AES to fully understand the process using R.Phan's paper as a reference. But I don't ...
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Differential cryptanalysis of modes of operation

It is not quite difficult to understand the idea of differential cryptanalysis applied to a standalone block cipher. The method investigates, how differences of plaintext evolve while going through ...
2 votes
1 answer
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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 ...
0 votes
1 answer
99 views

How to evaluate the minimum complexity of the key recovery when the success probability p is given?

Since the practical security of a symmetric-key primitive is determined by evaluating its resistance against an almost exhaustive list of known cryptanalytic techniques. My problem is that could we ...
2 votes
2 answers
190 views

Breaking the Even-Mansour Cipher with Quantum Period Finding: Probability of unwanted collision

The paper Breaking Symmetric Cryptosystems using Quantum Period Finding shows how to break the Even-Mansour Cipher using Simon's algorithm. The Even-Mansour uses two keys $k_1, k_2$ and a random ...
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Writing a specific position of AES state in a specific round in terms of Key bytes

Suppose we manipulate the zeroth byte of AES state after the 9th round ShiftRow operation and we want to see its effect on the ciphertext. The propagation of the error effect is demonstrated in the ...
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Cryptanalyzing a hash compression function

I'm designing a hash function which uses a double-tree construction and a compression function $c(s,A,B,C,a)$ ($s$ and $a$ may be omitted when there's only one of them) where $s$ is a set of three ...
2 votes
1 answer
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What are the RCons for mini-AES if you want to encrypt more than 2 rounds?

I'm implementing impossible differential cryptanalysis on mini-AES using Raphael phan's paper. I've coded mini-AES using Raphael phan's first paper on the structure of mini-AES, where he only mentions ...
2 votes
1 answer
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how to build textset for Impossible Differential Cryptanalysis on IDEA?

I'm implementing impossible differential cryptanalysis on 3.5 round IDEA using the methods in "Miss in the middle attack on IDEA and Khufu" paper. In the first step, I need to provide $2^{32}...
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Are there any papers talking about generating the pairs used in differential cryptanalysis or impossible differential Cryptanlysis?

I'm trying to implement impossible differential cryptanalysis on IDEA cipher based on the Miss in the middle attack on IDEA and Khufu paper. I'm trying to implement the attack on 3.5-Round IDEA and I ...
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1 answer
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Differential trails in differential cryptanalysis

From section 4.4 of this book https://www.ic.unicamp.br/~rdahab/cursos/mo421-mc889/Welcome_files/Stinson-Paterson_CryptographyTheoryAndPractice-CRC%20Press%20%282019%29.pdf I'm confused on how the ...
7 votes
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937 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?
2 votes
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how to build the plaintext structure for impossible differential cryptanaysis on IDEA?

I'm trying to implement impossible differential cryptanalysis on 3.5 round IDEA using Miss in the Middle Attack on IDEA and Khufu paper as a reference and I'm stuck on the first two steps of the ...
2 votes
2 answers
114 views

Differential Privacy with Outliers

To use the Laplace mechanism, we have to get the global sensitivity of a query function. What do we do in the case where there is one huge outlier(or multiple outliers) in the dataset such that the ...
4 votes
2 answers
254 views

Best complexity of guessing difference of AES-256 outputs

Suppose we have two plaintexts $m_1$ and $m_2$ such a way that $|m_1| = |m_2| = 128 $ and these two plaintexts are different just in one bit. Now suppose we know the value of $c_1 = AES_{k}(m_1)$($|k|...
2 votes
1 answer
298 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 ...
1 vote
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What's the average time to generate IDEA pairs?

I'm trying to implement impossible differential cryptanalysis on IDEA cipher based on the Miss in the Middle Attacks on IDEA and Khufu, I've started by implementing the cryptanalysis on 3.5-Round IDEA ...
1 vote
1 answer
146 views

Differential cryptanalysis - how to extend the attack to rounds before the last?

Suppose that we have a block cipher such that the last round of the cipher depends on half of the key and the penultimate round uses the other half. Suppose also that I attacked the last round using ...
6 votes
2 answers
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Cryptanalysis and weaknesses of SEED cipher

I've discovered that a client has SEED enabled in their SSL ciphers, and would like to know a bit more about it from a security perspective. The Wikipedia article doesn't mention any flaws, yet I've ...
1 vote
1 answer
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differential diffusion property of addition in SPECK cipher

I'm studying Impossible Differential Cryptanalysis of SPECK paper and I'm having trouble understanding the differential diffusion property of addition in page 19 which is as follows: can someone ...
1 vote
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Statistical Cryptanalysis. Would one "reverse" weak key schedule algorithms or peel off each one of internal rounds?

The context is iterated ciphers. Regarding Differential and Linear Cryptanalysis, the methods seem to make a cryptanalyst able to do an educated guess on a partial subkey (e.g. bits from the last ...
1 vote
1 answer
219 views

What is a differential attack on a hash function? How would one attack a SHA algorithm and what would achieve?

Currently, I have been assigned to attack a reduced version of SHA-1. What are we trying to achieve? How do we attack it?
19 votes
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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 ...
2 votes
2 answers
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How do we find differentials in differential cryptanalysis when we don't the details about the S-boxes

I m new to cryptanalysis and trying to understand differential cryptanalysis. I have read the paper by Howard M. Heys. I understood the concept of differentials but I m not able to understand how to ...
1 vote
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Differential analysis of SPN

Reference : Tutorial by HM Heys If we find a differential trail that holds with some non negligible probability for n-1 rounds for a n rounds SPN structure, then we can recover some of the bits of the ...
4 votes
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Differential and Linear Cryptanalysis

I have been reading about differential and linear cryptanalysis. They were mainly introduced by Adi Shamir and Biham to show the weakness of DES. However, many articles state that differential and ...
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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 ...
3 votes
1 answer
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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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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 ...
2 votes
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Complexity of Boomerang Attack on COCONUT98

I am trying to understand the paper The Boomerang Attack from David Wagner. On page 162 about complexity of boomerang attack the paper says that: The attack requires $8 \cdot 2 \cdot 32 \cdot 2^{32} ...
3 votes
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What are "unspecified" differentials in a differential characteristic?

I've been studying many papers on differential cryptanalysis and I see that in the published differential characteristics, such as in the appendices of [1], [2] and [3], some differences are left &...
3 votes
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How exactly to concatenate two differential trails to form a boomerang disguisher in practice?

I've been reading many papers on boomerang/rectangle attacks. The general strategy is to find two trails for a small number of rounds and then concatenate them to form a longer distinguisher. ...
1 vote
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103 views

How do we know a single differential/linear trail dominates the others?

I have read the proof of AES's resistance against differential cryptanalysis. In the proof the authors show that there is no single differential trail with prop ratio higher than $2^{-300}$ over 8 ...
2 votes
1 answer
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Why the differential cryptanalysis complexity is linear with inverse of the probability while linear cryptanalysis is quadratic with the bias inverse?

I am trying to understand the analysis of the complexity of Differential Cryptanalysis versus the complexity of linear cryptanalysis. In differential cryptanalysis the number of required texts is $\...
3 votes
1 answer
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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-...
6 votes
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Finding differentials and space complexity

In Differential Cryptanalysis of DES-like Cryptosystems by Biham and Shamir, they provide examples using differentials inputs such as $\Omega_p = 00\ 80\ 82\ 00\ 60\ 00\ 00\ 00_x$. Most of article is ...
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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 ...
3 votes
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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 ...
2 votes
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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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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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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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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 ...
1 vote
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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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Are the weaknesses of my s-boxes attackable?

I got specific problem with my s-boxes in $128$-bit block cipher. One round of encryption is like that: input - sbox - reverse block - $sbox^{-1}$ - output Every s-box got specific $128$-bit key. $...
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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 ...