Maximum Distance Separable (MDS) Matrices are used for providing diffusion in a cipher. How to test the strength (with respect to cryptographic properties) of an MDS matrix used in a cipher?

  • $\begingroup$ What properties does the cipher need to assume from the MDS matrix? If it's just whether it is, in fact, MDS, well, that's straight-forward to test... $\endgroup$
    – poncho
    Jul 13 '18 at 22:46
  • $\begingroup$ The only strength any matrix can contribute to a cipher is diffusion. Since matrix multiplication is linear. $\endgroup$
    – kodlu
    Jul 14 '18 at 3:33
  • $\begingroup$ @kodlu: however, one could design a cipher which is weak with one specific MDS matrix, and strong with another. Hence, it can be more than just the MDS properties; it can also be how well it plays with the rest of the cipher... $\endgroup$
    – poncho
    Jul 14 '18 at 13:51
  • $\begingroup$ @poncho, could you clarify with an example? I can ask a separate question if you like. I havent seen MDS used differently than in AES, and I thought ( beyond efficiency) any MDS matrix would have the same diffusion/security properties since all MDS codes with the same parameters have the same weight distribution. $\endgroup$
    – kodlu
    Jul 14 '18 at 23:10
  • $\begingroup$ @poncho any update on this? $\endgroup$
    – kodlu
    Sep 19 '20 at 6:38

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