# 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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### 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 ...
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### Risks using .NET RijndaelManaged with static Key and IV

A company I'm consulting for has a (quite old) home grown web SSO solution based on an encrypted cookie. The auth flow looks more or less like this: User hits protected page on integrated site Site ...
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### Is Rfc2898DeriveBytes random? C#

I am trying to wrap my head around encryption in .NET. I am trying to implement a simple solution in ASP.NET Core to encrypt a cookie containing some non-meaningful numbers to outsiders. I need to be ...
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### Implications of identical round keys in AES (Rijndael)

When reading up on the Rijndael key schedule, I learned that the master key itself is used as a round key directly before the key schedule generates additional round keys. When a 256-bit key is used, ...
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### AES S-box input and output question

I am new to cryptography. I am looking to understand how to answer this question from my class: Find below the S-box of AES. Given the input 01010011 in binary, calculate the output.
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### Replacing a block cipher's key schedule with a stream cipher

Take Rijndael (AES) of block size 128 and reformulate it with a tweakable number of rounds and no key schedule. Suppose we obtain: Rijndael128(r, k) where r is ...
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### How to find the right additive polynomial in inverse affine transformation in AES

Addition polynomial affine transformation rijndael is (x^7 + x^6 + x^2 + x) The affine transformation represented in A(x) A(x) = (x^7 + x^6 + x^2 + x) + a(x)(x^7 + x^6 + x^5 + x^4 + 1)mod x^8 + 1 ...
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### AES S-Box implementation: from a byte-by-byte to 2-bytes-by-2bytes?

The S-Box in AES encryption is a byte substitution step. Is it possible to perform the substitution 2 bytes at a time, rather than 1 byte? What are the challenges/trade-offs involved?
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### AES key expansion for 192-bit

In AES-192 key expansion there are 12 rounds and 52 keys. I am not sure why 52 keys are derived since each block consist of 4 rows and 6 columns (192 bit keys). So if the block is 4 x 4 then we ...
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### AES - Finite Field Multiplication on 8 Bit Platform

Section 4.1.1 "Finite Field Multiplication"(page 53) of "The Design of Rijndael", it states How the equation 4.1 has been formed and transformed into equation 4.2? In section 2.1.6 "Polynomials ...
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### Implement Twofish cipher with 16-bit blocksize?

I've seen implementation of Rijndael cipher with 16-bit blocksize. And I have also tried to implement 16-bit Rijndael cipher by myself with only a little sneak peeking at the example of the ...