# Questions tagged [cryptanalysis]

Analysis of individual security aspects of a cipher or algorithm, not the security of a cipher or algorithm in general (which would lean towards “algorithm-design”).

1,438 questions
Filter by
Sorted by
Tagged with
13 views

### Which among the following is a method of encryption where units of plain text are replaced with cipher text according to a fixed system? [closed]

Substitution Cipher DES AES All of the above Basically, I am confused between all three. Because all of them are symmetric. Yet, AES and DES are block ciphers. Any idea?
53 views

### Problem with implementation of Enigma Machine

I'm having trouble making an implementation of Enigma Machine in VBA. My question is about implementing the rotors and their move. To be more precise, I will show below the way that I code my Enigma ...
41 views

### Is Mersenne Twister hard to break if it has a reduced output?

I was reading this challenge, which proposes to clone (or recover) the internal state of the MT19937 just by applying the inverse process to each output (624 consecutively words). Mersenne Twister's ...
104 views

### About the complexity of a path finding attack for a path encrypted with a block cipher (like AES). How many AES calculations count as secure?

Out of $N = s^3$ total points we pick a starting point $p$ and an end point $q$ with $$p=(p_1, p_2)$$ $$q=(q_1,q_2)$$ $$p_1,q_1 \in [0,s)$$ $$p_2,q_2 \in [0,s^2)$$ We want to find a path in between ...
67 views

### Why would the same cipher structure have a different optimal attack for different bit widths?

I'm going to use the Simon Cipher as an example, but I want to frame the question to be more general. Why would the same cipher structure have a different optimal attack for different bit widths? I ...
63 views

### Why is ShiftRow important in AES?

I came across a comment about AES 128 without ShiftRow. I want to use this weakness to perform an attack. So far, I get that It possible to divide in 4 independent blocks of 32 bits. So we can launch ...
1 vote
46 views

### Linear cryptanalysis resistance of AES Sbox

If you look at the AES Linear Approximation Table (computed for example with Sage) you will see there are many entries with what looks like a high bias of -16 ("absolute bias" scale). I ...
48 views

### What is digram analysis?

so I wanted to ask something since I just learned about cryptography. Here where I have the task to write an essay on cryptography and the title I have to do is introduction digram analysis. However, ...
36 views

### Scyther related questions for handling/splitting values and verifying hashes

While implementing a protocol in Scyther, I need help with the following questions - How do we split a particular message/variable into two parts in Scyther? (For eg. if I have value R in my protocol ...
1 vote
53 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 ...
63 views

### Attack against stream cipher (LFSR with ASCII)

I'm reading Understanding Cryptography by Christof Paar and Jan Pelzl. In chapter 2 (Stream Ciphers) there's a question that goes like this: Assume we have a stream cipher whose period is quite short....
105 views

85 views

76 views

### Calculating statistical distance for simple addition cipher?

I'm looking at the solutions to this problem set for self study. One of the questions is to calculate the statistical distance for the following scheme: The message space is equal to the key space, ...
### How to Prove matrix $m \times m$ is invertible is equivalent to be $LI$ over $\mathbb{Z_{2}}$?
I came up with one problem that says that a $m \times m$ matrix is invertible is the same as to say that its rows are LI (linearly independent) over $\mathbb{Z_{2}}$. First of all, I'd like to know ...