[KimDaBa] new feature: IPTC keywords

[Robert L Krawitz]

   Date: Sun, 23 Oct 2005 22:02:09 +0200
   From: Marco Molteni <molter at tin.it>

   On Sun, 23 Oct 2005 15:11:16 -0400
   Robert L Krawitz <rlk at alum.mit.edu> wrote:

   [..]

   >    From an IPTC point of view, the keywords must stay in the image
   >    since the beginning, without the need of an export phase. Otherwise
   >    the potographer would have to remember that he cannot upload photos
   >    directly but that he has to export them before.
   > 
   > BTW, how does this interact with the new Canon cameras that can verify
   > that a photo is not modified (presumably using a cryptographic
   > checksum or the like)?

   I don't know, I wasn't aware of this feature.

   But I don't see a problem: keywords, be it jpeg or iptc, are stored
   in a specific area of the file, so it is always possible to go back
   to the file image without keywords.

Again, it depends upon how it works.  It may be that it ignores the
keyword portion of the file.

   But it is amazing, since I always though about something similar.
   Too bad Canon beated me to it ;-)

   My idea was: how to go back to a unique property of film as opposed
   to digital: the fact that if you don't trust a print you can
   analyze the negative to see if there are modifications (putting
   aside the fact that a negative too can be modified).

   I though that the only way was for the camera to store a list of
   serial numbers and associated message digest (say MD5 or SHA or
   whatever).

   But then I hit a block because the question is: how do you trust
   the list that comes out of the camera? Did Canon solved this?

It doesn't actually have to store this.  What it might do is sign the
file with a particular key (presumably each camera has its own key
buried deep inside a ROM), and then either the camera or Canon's
software can verify the file's signature.  As long as the
camera-specific key is secret -- and the software is trusted -- you
can verify the image.

This kind of capability is very important for law enforcement purposes
-- an investigator can prove in court that the image was not tampered
with.

-- 
Robert Krawitz                                     <rlk at alum.mit.edu>

Tall Clubs International  --  http://www.tall.org/ or 1-888-IM-TALL-2
Member of the League for Programming Freedom -- mail lpf at uunet.uu.net
Project lead for Gimp Print   --    http://gimp-print.sourceforge.net

"Linux doesn't dictate how I work, I dictate how Linux works."
--Eric Crampton