My prof said that the last round of the AES algorithm doesn't use the MixedColumns layer, yet this doesn't decrease security. If so, why the MC layer is used in the other rounds?

  • $\begingroup$ indeed, it's amazing how people don't even do a basic search on keywords, before asking the same question. $\endgroup$ – kodlu Dec 5 '19 at 17:11
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    $\begingroup$ @kodlu actually the question here is a little different, namely "why is MC used in the other rounds" $\endgroup$ – Richie Frame Dec 6 '19 at 0:53
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    $\begingroup$ Richie is right $\endgroup$ – AleWolf Dec 6 '19 at 9:32
  • $\begingroup$ @AleQuercia Do you understand why MixColumns is important in the first place? $\endgroup$ – forest Dec 8 '19 at 3:23
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    $\begingroup$ First I thought this wasn't a dupe, because the question in the body of the post is perpendicular to the one in the title, but as the dupe pointed to by kelalaka also includes a description why it is used in the first place, I'll close it none the less. If there are any remaining questions about it please ask them separately after checking if it has been asked before. $\endgroup$ – Maarten Bodewes Dec 8 '19 at 17:16

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