# Questions tagged [rijndael]

Rijndael is a family of symmetric block-ciphers with block and keys sizes of 128, 160, 192, 224, or 256 bits.

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### How does the key schedule of Rijndael looks for keysizes other than 128 bit?

It said in Wikipedia that: [....] Rijndael can be specified with block and key sizes in any multiple of 32 bits, with a minimum of 128 bits. The blocksize has a maximum of 256 bits, but the keysize ...
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### Advantage of AES(Rijndael) over Twofish and Serpent

I'm trying to figure out a suitable encryption technique and after reading a bit, I figured the current AES 128-bit encryption is suitable for what I'm trying to do. However, this is more due to the ...
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### How to find the AES branch number?

By definition, branch number Definition: The branch number of a linear transformation $F$ is $$min_{a\neq0}(W(a) + W(F(a)))$$ Source here (7.3.1) For AES MixColumns $a \in GF(2^8)^4$ since ...
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### Choice of multiplication polynomial in Rijndael s-box affine mapping

The Rijndael specification details the design choices for the s-box in section 7.2. They describe the choice of affine mapping as follows: We have chosen an affine mapping that has a very simple ...
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### How were the AES key and block length subsets of Rijndael selected?

My intuition tells me it's a trade off between speed and security, but how did the standardisation process select these three seemingly arbitrary key lengths (namely, AES-128, AES-192, AES-256).
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Section 3.4.3 "The MixColumns Step"(page 39) of "The Design of Rijndael", it states The columns of the state are considered as polynomials over $\operatorname{GF}(2^8)$ and multiplied modulo $x^4 ... 1answer 4k views ### How can I calculate the Rijndael SBox? I would like to implement the Rijndael subBytes() operation using calculation instead of tables, because I like to play with this on different wordsizes, as an ... 1answer 2k views ### Does changing the order of the steps within a round affect the security of AES? I was trying to understand the internal structure of AES (Advanced Encryption Standard) The Standard order of steps within a round: Substitute Bytes Shift Rows Mix Columns Add Round Key Substitute ... 1answer 734 views ### 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 ... 1answer 485 views ### Who said "32 round Rijndael" in the third AES Conference This is a historical question. In the third AES Conference of NIST (AES3), April 13-14, 2000, New York, near the end of the conference, one representative for each of the last 5 candidates sit on a ... 1answer 3k views ### Can neural cryptanalysis be applied to AES? In this Wikipedia article about Neural cryptography (section applications) it states: In 1995, Sebastien Dourlens applied neural networks to cryptanalyze DES by allowing the networks to learn how ... 2answers 3k views ### AES - What is the advantage of a 256-bit key with a 128-bit block cipher? [duplicate] I'm just trying to wrap my mind around the decision to select the 128-bit Rijndael as the AES cipher, even with 192-bit and 256-bit keys. Even with a 256-bit key, you only get 2^128 possible outputs ... 1answer 882 views ### How to perform the modular reduce of Rijndael's finite field I am trying to understand how to calculate the modular reduction of Rijndael's finite field. The example on this page says that {53} • {CA} = {01}, because ... 1answer 15k views ### Difference between Rijndael 128 / 256 blocksize implementations? (and impact of block size in general) Can anyone shed some light onto the advantages/disadvantages of using Rijndael with 256-bit block size, as opposed to the 128-bit (AES) implementation? (please note: I'm not referring to key-size here)... 2answers 1k views ### Need help understanding math behind Rijndael S-Box in Rijndael SubBytes() step all bytes of input block are substituted based on a lookup table S-Box. S-Box is initialized by taking all elements of$GF(2^8)$, ... 1answer 345 views ### Does the key schedule function need to be a one-way function? For some key schedule$e_n(e_{n-1}(k))$(where$e_{n-1}(k)$is the result of the previous round) , does$e$need to be a one-way function? In the case of DES or Rijndael the key schedule doesn't ... 1answer 494 views ### Increases in the AES S-box AES uses one S-box to substitute all 16 bytes in one round. Will using 16 different S-boxes (with cryptographic properties similar to the AES S-box (i.e., non-linearity of 112, differential ... 1answer 2k views ### Is it necessary for the Rijndael polynomial to be primitive? I am working on selecting a S-box for my Cipher (Similar to AES). I found out there are 30 irreducible polynomials and over 16 primitive polynomials of degree 8. Is it necessary to choose a primitive ... 1answer 2k views ### Calculating Multiplicative Inverse for Rijndael S-box using EEA I am currently learning, and I'm stuck on something that I thought is very simple. On many academic sources they suggest using Extended Euclidean Algorithm to calculate the multiplicative inverse for ... 1answer 2k views ### Why is AES unbreakable? Why is it said that AES is unbreakable? Brute force attacks would take years to crack it, so is it possible to crack it if the computational speed of machines increase in the following decade? 1answer 1k views ### How do Käsper and Schwabe's Bitsliced AES Mixcolumns work? The only way I see it possible to do the matrix-multiplication in the MixColumns operation of AES is by shifting the bits in the multiplied number, and then reduce with the polynomial if needed. ... 1answer 395 views ### Rijndael S-boxes: Where do the$\mu$and$\nu\$ polynomial ring elements come from?

I've asked some other questions before about Rijndael's S-boxes, and step by step I'm coming to an understanding; but those steps often guide me to new questions. I did some lines of code to ...
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### Why was Rijndael the only cipher to have a variable number of rounds?

Rijndael was the only AES candidate which defined a different number of rounds for their 128, 192, and 256-bit versions (10, 12, and 14, respectively). The others had a fixed number of rounds (32 for ...
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### Choice of reduction polynomial in Whirlpool's internal cipher

Whirlpool is an interesting little hash function in the Miyaguchi-Preneel family. In my mind, it's most interesting feature is the design of internal cipher W, where the distinction between key and ...
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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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### What is the fastest block cipher in the (Intel) world?

In AES competition,Rijndael cipher obtained first rank and become Standard and Serpent, Twofish, RC6 and MARS obtained another ranks and I know that Serpent took second rank because it was slower than ...