[FFmpeg-devel] Help: AES GF Multiply
Reimar.Doeffinger at gmx.de
Mon Jul 30 21:42:51 CEST 2012
On Mon, Jul 30, 2012 at 04:56:05PM +0200, Michael Niedermayer wrote:
> about aes.c, if you export the log8 alog8 (thats exp) tables
> it should be trivial to do a multiplication with them
You will also need to export an initialization function, at least it
seems not nice to depend on the full AES initialization.
And to simplify the whole mathematics to concrete usage, the
alog8[log8[x] + log8[y]]
(assuming x and y != 0, if either is 0 the result is 0 as usual)
Doing it manually without the exponential/log lookup trick is
of course possible but quite a pain.
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