# Questions tagged [spn]

A Substitution-Permutation-Network is a structure that has been used to create a number of different block ciphers (e.g., AES, Picollo, Present...)

14 questions
83 views

### Can the S-Boxes and the P-Box commute?

Consider an SPN operating on blocks of size $m\ell$ bits. Suppose that each round consists of adding the round key (bitwise xor), applying $m$ S-boxes (so that each S-box operates on $\ell$ bits), and ...
1k views

### Linear Approximation Table of S-Box for SPN

I havejust gotten to Linear Cryptanalysis and I'm studying some material on Linear Attack's against SPN. I see here http://www.cs.bc.edu/~straubin/crypto2017/heys.pdf on page 11 that they calculate ...
84 views

### Classify a (block) cipher

Can someone help me to classify a cipher algorithm? It's: a block cipher (1 block = 6 bit); a hashing algorithm (i.e. data is ...
59 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?
403 views

### Substitution-permutation network visualizer

I'm doing differential analysis of a toy block cipher in which I've to extract the differential characteristic of the first n-1 rounds. However, I can't do that very well as I can't see the network ...
92 views

### What does this notation means $\mathbb{F}_{2^{-}}$?

I have seen various papers to use this notation $\mathbb{F}_{2^{-}}$ to describe the diffusion layer. As for example the permutation in AES (MixColumns). So, we have a field with order of 2, what does ...
258 views

### Alternatives to sbox's for diffusion?

Are there any other alternatives to Sbox's or SP networks to provide diffusion preferably more basic alternatives which still provide a good degree of security?
420 views

### substitution-permutation network construction

I want to understand more about substitution-permutation network, if we modify it instead of carrying out the key-mixing, substitution, and permutation steps in alternating order for r rounds, the ...
106 views

### Using a round function intended for an SP network in a Feistel network?

If I use the round function from a secure SP network (such as AES) and use it in a Feistel netwok, is this a good starting point for the second cipher? My thought is "yes" because: it already has ...
2k views

### What is the diffrence between Feistel networks and SPN?

I recently read about the concept of Feistel Networks and Substitution Permutation Networks but what is exactly the difference between the two ?
274 views

### Question about the security of Substitution-Permutation Network

In general, we execute key-mixing, substitution and permutation sequentially in a single round in a n-round SPN, but if we execute n-round key-mixing firstly, n-round substitution secondly and n-round ...
572 views

### What is the intuition behind AES or SPN?

I'm new to cryptography and have just encountered AES and SPN. I would like to know how the S-box, permutation step and the MixColumn step help improve security. It seems to me (perhaps mistakenly) ...