I am doing a project on the Rijndael Algorithm. I have already written the encryption code which produces the correct output. Now I want to implement decryption as well. I'm doing using VHDL, targetting the Xylinx platform.

Can anyone help me coding for ADD_ROUND_KEY step in decryption.

  • $\begingroup$ The ADD_ROUND_KEY step is identical for both encryption and decryption; if you have the coding for the encryption step, just reuse that. $\endgroup$
    – poncho
    Oct 26, 2015 at 14:25
  • $\begingroup$ thanks for ur ans.... i hav done that, but not coming.... are the values of RCON also same? $\endgroup$ Oct 26, 2015 at 14:32
  • $\begingroup$ Have you coded for both encryption and decryption? $\endgroup$ Oct 26, 2015 at 14:33
  • 2
    $\begingroup$ Actually, you run through the key scheduling backwards (and so the last subkey for the encryption direction is the first subkey for the decryption direction). Or, are you expanding the subkeys at the same time you're performing the encryption? $\endgroup$
    – poncho
    Oct 26, 2015 at 14:34
  • $\begingroup$ I am coding encryption and decryption both seperately..... $\endgroup$ Oct 26, 2015 at 14:36


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