I once read somewhere that the keys determine the S and P boxes. If so, how does that work?

  • $\begingroup$ Commenting not answering b/c I'm not sure if I recall correctly. My recollection is that with AES (per your question), the substitution and permutation operations are not key-dependent. However, with some ciphers (e.g. Blowfish), the operations do depend on the key. $\endgroup$
    – Dan
    Nov 2, 2019 at 20:54
  • 2
    $\begingroup$ Where did you read that the keys determine the S and P boxes for AES? Considering that AES does not have a P-box as such, the source is suspect. $\endgroup$
    – Ella Rose
    Nov 2, 2019 at 22:51
  • $\begingroup$ I think I was mistaking with blowfish then...but if the substitution-permutation boxes are fixed, then anybody can reverse the encryption process right? Now I know if this was true then it wasn't the standard for the government, but still, if they're fixed, how? $\endgroup$ Nov 3, 2019 at 15:09
  • $\begingroup$ Have you read the definition of AES, specifically what the steps involved in it are? $\endgroup$
    – Ella Rose
    Nov 3, 2019 at 15:23
  • $\begingroup$ @Ella Rose no..but they have to be key independent right? Cuz if they're fixed then anybody can reverse the ciphertext right? $\endgroup$ Nov 3, 2019 at 15:29


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