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Questions tagged [diffusion]

Diffusion refers to the property of an encryption primitive that small changes in the plaintext result in big changes in the ciphertext and vice-versa.

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AES: Why ShiftRows() before MixColumns()? [duplicate]

In above picture you can see a AES state array over 2 rounds through the S- and P-Boxes of AES. It's taken from here and intends to show how 2 rounds of transformation are necessary to achieve full ...
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Application of MDS matrices in serial and round-based implementations

We know that MDS matrices are used in the diffusion layers of block ciphers. My question: what types of MDS matrices can be applied to serial or round-based implementations or both of them? I ...
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Effect of block size on diffusion rate

I've always been under the belief that larger block sizes require more rounds to achieve full diffusion. Rijndael, SPECK, and SIMON, for example, have a round multiplier based on the block size. The ...
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Algorithm for symmetric encryption (diffusion without confusion)?

I'm looking for a symmetric encryption algorithm with specific characteristic. Having a key $k$ a message $m$ returns a ciphertext $c$, where $E_{k}[m] \rightarrow c$ It should be hard to perform a ...
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AES Diffusion at Block Level

AES provides diffusion at the block level by implementing the ShiftRows and MixColumn sublayers. The former permutes data on a byte level, wheres the latter combines blocks of four bytes. Can it ...
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Early propagation of carries in the BLAKE hash function

The BLAKE paper uses round constants derived from $\pi$ to improve diffusion, even if the additions modulo $2^{32}$ are replaced with bitwise XOR when processing a null message and null initial state: ...
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What's the difference between confusion/diffusion and mode of operation?

I understand the concepts of confusion (substitution) and diffusion (permutation). My understanding of what a mode is that it's an algorithm that lets us encrypt arbitrary message size. i.e. AES is ...
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Cryptographic Strength of MDS Matrix

Maximum Distance Separable (MDS) Matrices are used for providing diffusion in a cipher. How to test the strength (with respect to cryptographic properties) of an MDS matrix used in a cipher?
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Understanding the wide trail design strategy

I am trying to understand the wide trail design strategy. I have read the paper which describes it from the point of view of AES. From what I understand, it is a technique to increase diffusion in a ...
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How do we reduce the multiplications in the AES mix column layer using $x^4 +1$

I recently learned AES uses $x^4 +1$ to reduce the multiplications in the MixCol layer. However, I used $p(x) = x^8 + x^4 + x^3 + x + 1$ not knowing it was the wrong polynomial and got the correct ...
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How can I get the binary form of AES's MDS matrix in MixColumns tranformation?

I need to write a procedure for calculating the MixColumns's operation result in the following form: $M*X^T,$ where $M$ is a 128x128 binary matrix, $X$ is a 128-bit vector (the state). My question ...
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Confusion and Diffusion in the AES functions

I am pondering, how each of the four functions that a full AES round does consist of (Add Round Key, Substitute Bytes, Shift Rows and Mix Columns) add to the confusion and diffusion of the full AES. ...
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Why did they choose $x^4+1$ for the MixColumns step in Rijndael/AES?

In The Design of Rijndael page 39, It describe the design criteria for MixColumns step Dimensions. The transformation is a bricklayer transformation operatingon 4-byte columns. Linearity. The ...
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What is an advantage of MDS matrices in block ciphers?

I saw the several articles about MDS matrices. They said that, one goal of MDS matrices is to protect the block ciphers against linear and differential attacks. My question is: For example in the ...
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356 views

Prove the branch of number of Advanced Encryption Standard

In the Advanced Encryption Standard (AES) document: page 27 section 7.3.1, It defines branch number. It said " Let F be a linear transformation acting on byte vectors and let the byte weight ...
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Full diffusion or Partial diffusion between s-box applications?

In regards to maximizing active s-boxes: is it advantageous to apply the non-linear layer after complete diffusion of the state, rather after then partial diffusion? Using AES as an example, with ...
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1answer
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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 ...
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How 2 rounds in AES achieve full diffusion?

I have read somewhere that 2 rounds is AES provide full diffusion. So I looked it up to find out what it exactly meant. In The Design of Rijndael page 41, section 3.5 and it states that: Two ...
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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?
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How does AES introduce confusion and diffusion?

I know that in AES the shift-rows and mix-columns operations introduce diffusion, but I don't understand how they create diffusion. Also, I know the add-round-key operation creates confusion, but I ...
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How were the diffusion statistics for norx calculated?

I was reading the norx specification and came across this section, which provides some kind of statistics about the diffusion of the norx round function. However, I don't see how these values were ...
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Does the One Time Pad rely on confusion or diffusion?

From what I could research, XORing a random key adds confusion. But I do not undertand the rationale for that classification. Shannon's confusion is supposed to obscure the relationship between the ...
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Encrypt-Mix-Encrypt: Full Diffusion?

I've read "A Parallelizable Enciphering Mode" by Halevi and Rogaway about the encrypt-mix-encrypt mode for ciphers and was asking myself if this mode provides "full" diffusion. So if an attacker ...
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Block cipher mode with diffusion on ciphertext

As I understand, diffusion property in AES-CBC ensures that one-bit change in plaintext will yield changes in all following blocks in ciphertext upon encryption. I'm looking for algorithm that will ...