[FFmpeg-devel] [PATCH] DES en-/decryption

[Reimar Döffinger]

Hello,
On Sun, Oct 14, 2007 at 02:05:36AM +0200, Aurelien Jacobs wrote:
> On Sat, 13 Oct 2007 22:15:42 +0200
> Reimar D?ffinger <Reimar.Doeffinger at stud.uni-karlsruhe.de> wrote:
[...]
> > If any of the "Makefile-guys" have some time, maybe you could see if you
> > can come up with something? I'd expect this could be used in some other
> > code as well (I hope others agree this would be nice).
> 
> I haven't really looked at the code, but isn't it possible to simply
> generate this table in a des_init() function or something like that ?

Of course, but then 1) the 256 byte S-box table must be kept 2) it will
use up RAM that can't simply be swapped out to the binary.

> > Index: libavutil/des.h
> > ===================================================================
> > --- libavutil/des.h	(revision 0)
> > +++ libavutil/des.h	(revision 0)
> > @@ -0,0 +1 @@
> > +uint64_t ff_des_encdec(uint64_t in, uint64_t key, int decrypt);
> 
> I think you should add multiple inclusion protection.

Why? As long as there are only function prototypes there should not be
any reason to use them.

Greetings,
Reimar D?ffinger