# Tagged Questions

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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### How do I apply differential cryptanalysis to a block cipher?

I have read a lot of summaries of block ciphers particularly with regards to the NIST competitions stating that reduced-round block ciphers are – for example – vulnerable to differential cryptanalysis....
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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 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 ...
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### differential cryptanalysis cipher for the final round

I have a problem to find the sub-key. The system is… For each round, we make the following stage: We add the round key $K_i$. Substitution : we have 8 blocks of 4 bits, and an S-box ...
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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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### 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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### 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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### Differential Fault Analysis of AES

Let's say: an error is induced into an implementation of the AES-128 to produce a faulty ciphertext. The error is a one-byte eror and is always induced on the last state byte, during round9, before ...
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### How to prove a cipher resistant to differential cryptanalysis?

How do you prove that a cipher is resistant to differential cryptanalysis? It's said that Rijndael has been proven resistance to differential cryptanalysis. How do cryptographers do that?
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### Performing differential cryptanalysis for randomly generated S-boxes

As far as I know, performing differential or linear cryptanalysis always requires a knowledge of the S-boxes' content and order. Yet in Bruce Schneier's Applied Cryptography, it is stated that random ...
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### How do we find the subkey out of a differential cryptanalysis?

I understand the differential cryptanalysis up to the "finding the last subkey" part. If XORing with the key doesn't change the differentials, how can testing different key affect the equations we ...
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### SHA-1 collision resistance

I'm researching on the SHA-1 algorithm and looking for reasons why it has fallen prey to differential cryptanalysis. I have read the research papers by Merc Stevens and Wang both of which describe how ...
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### Differential Cryptanalysis

How do I find the differential characteristics using techniques Shrinking ? How do I extract the key on Differential Cryptanalysis using the technique Shrinking in Blockcipher Algorithm? Shrinking ...
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### Applying differential cryptanalysis to ciphers with addition mod $2^{32}$

I am studying differential analysis and have a question. Consider the following simple cipher: $$c_1 = S(m_1 \oplus k_1) \oplus k_2$$ (Plaintext $m_1$ xor with key $K_1$, then result goes into an S-...
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### What is the complexity for attacking 3DES in linear or differential cryptanalysis?

I know that 3DES is NOT vulnerable to DC , LC . But is it because the attacks requires too many input\output pairs ? Or because it's impossible ? (i.e requires more than 2^64 pair )
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### Comparing Difference Distribution Tables

I have been studying the Diff. Cryptanalysis and finding it hard to do a problem. The problem is I have calculated the tables programmatically and found that the second table has a max value of 6 ...
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### 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 ...
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### 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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### How to find an impossible differential?

Given an arbitrary SPN-based cipher with X rounds. How to find an impossible differential for this cipher? What are strategies to find one?
I'm currently carrying out a differential attack on the FEAL-4 algorithm, however I have hit a bit of a wall. Basically I attacked the final round first ($K3$) using the differential characteristic ...