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S-box in AES CCM 128 bit

I am working on encryption & decryption of data using AES-CCM.

While studying AES, I came across a word called S-Box.

What is S-Box, and the relationship with AES? How can it be calculated? Is it depends on symmetric key or not?

How will cypher text be generated in AES-CCM 128 bit?

Solution

  • The S-Boxes are a system that is used in symmetric cryptographic algorithms to substitute and obscure the relationship between the key and the text that you want to cypher.

    You can see more in this article. Here, you have a part:

    There are different types of cyphers according to their design [68]. One of these is the ​Substitution–PermutationNetwork (SPN) that generates the ciphered text by applying substitution and permutation rounds to the original text and the symmetric key to create confusion. To do this, it must be used the Substitution boxes (S-boxes) and Permutation boxes (P-boxes). The S-boxes substitute one-to-one the bits of a block of the input text in the round with bits of the output text. This output is taken as an input in the P-boxes and then it permutes all the bits that will be used as S-box input in the next round.