# Tag Info

Accepted

### Understanding the wide trail design strategy

Given the importance of the wide-trail strategy in modern symmetric-key cryptography, this question really deserves an answer (and a much better score). Since nobody else has tried, I'll give a brief ...
Accepted

### How 2 rounds in AES achieve full diffusion?

AES diffusion is taking cared of by 3 main functions: SubBytes Shift Rows Mix Columns SubBytes works as a 8-bit S-box. Thus if one bit change, the 8 bits of the byte are likely to change. With this ...

### How does AES introduce confusion and diffusion?

Put simply: The add key layer ensures the encryption function is only computable by someone who knows the key Adds some confusion because the key is (psuedo) random The subBytes s-box layer creates ...
Accepted

### Confusion and Diffusion in the AES functions

I should start by saying that the notions confusion and diffusion can not provide an in-depth understanding of the design of the AES, simply because they are not specific enough. Instead, the key to ...

### Which sub operation is more expensive in the AES encryption process?

The table lookup implementations usually combine the SubBytes and ShiftRows steps with the MixColumns step. Different implementations/hardware/etc make general statements impossible, but this paper ...
Accepted

### Prove the branch of number of Advanced Encryption Standard

The dear user @kodlu has answered to the similar question with excellent discussion but I want to answer with linear algebra argument. We have two definitions for MDS (Maximum Distance Separable) ...
Accepted

### How do we reduce the multiplications in the AES mix column layer using $x^4 +1$

The $x^4+1$ is implicit in the matrix. What you are doing is that you consider formal sums $z_0 + z_1 \alpha + z_2 \alpha^2 + z_3 \alpha^3$ for $z_i$ elements of the field $\mathbb{F}_{256}$, and a ...

### How can I get the binary form of AES's MDS matrix in MixColumns tranformation?

Concretely, given an element $x \in$ GF($2^8$), to multiply it by 2, we simply do a left shift and xor with 0b100011011 if the result of the shift gets above 0b11111111 (255). To multiply by 3, we ...