I was mentioning Fiestel Network in general. The comment wasn't
implied directly on AES and/or DES specifically.
As such I would still maintain that the essence of Fiestel remains in
its simplicity of Encryption and Decryption process which are reversal
of the process itself.
"The Feistel structure has the advantage that encryption and
decryption operations are very similar, even identical in some cases,
requiring only a reversal of the key schedule" -Wikipedia
Precisely the similarities between AES and DES are -
AES Round Key addition corresponds to DES XOR of subkey material with
the input to function f.
AES Mixcolumn corresponds to DES XOR of function f output with the
left half block.
AES ByteSub corresponds to function f in DES.
AES ShiftRow corresponds to DES permutation P.
Regards,
Shailesh
On Feb 18, 2009, at 12:01 PM, Terra Frost wrote:
On Tue, Feb 17, 2009 at 6:08 PM, Shailesh Rangari <shailesh...@gmail.com
> wrote:
- both use the 'Fiestel Network' (first used in Lucifer & DES). Its
essence
is Decryption is done by Reversing the order of Encryption.
That's incorrect. In DES, the only difference between the encryption
and decryption is the order in which the round keys are used. That's
pretty much the definition of a Fiestel Network.
In AES, in contrast, the differences between encryption and decryption
are a bit more pronounced. Take a look at fips-197.pdf#page=25 and
fips-197.pdf#page=19. The only function shared by both is
AddRoundKey. SubBytes and InvSubBytes differ in that they use
different S-Boxes, InvShiftRows and ShiftRows shift the rows in
opposite directions, and MixColumns and InvMixColumns with a different
fixed polynomial.
fips-197.pdf can be found here:
http://csrc.nist.gov/publications/fips/fips197/fips-197.pdf
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