Gail,
Yes, I understand that the 'Document Information Dictionary' alone is not
enough, also having the information in the image should be required. I just
wasn't sure where you were going with this.
As for you question; "maybe": depending on what the digital signature is used
for. If I generated a digitally signatured PDF/is doc on my system and placed
it on a web site, then someone transmitted that document using IPPFAX to someone
else, my original signature should not be used as a "Fax transmission header".
This is an interesting situation. Do we want to limit DSigs to just being used
for "transmission headers": I think not. Therefore, we can either have two
uses for them, or find another way to handle the "transmission header". We
could change the PDF/is spec to allow for more than one DSig (it is allowed in
PDF) very easily (one sentence in section 3.3.16). We would then have to
specify that a certain DSig is for "transmission header" and all others are for
"other purposes". Each PDF/is document would only be able to have one of these
"transmission header" DSigs. We could specify this using the DSig's 'Name' or
'Reason' fields having a special value for the "transmission header". Of
course, using DSigs this way would move DSig support for the Consumer and
Producer from 'Optional' to 'Required'. Do we want this? Using DSigs in this
way, I believe, is a superior way to tag a fax transmission to adding some image
of the information in the header of each page; but it has a cost. One other
benefit of this -- once the document is received, it can be printed out without
the header tag information in the printout, if desired.
If we do not want to use DSigs this way, we are back to using an image of the
header (are there other options?). We could specify that this image header as
part of the spec. We could specify it as a shared image for all pages of the
document. This would allow the recipient to print the document without the
header, if so desired. But, by doing this, we make it easier for someone to
replace the header during transmission. Hmmmm.
Comments?
-Rick
-----Original Message-----
From: owner-ifx@pwg.org [mailto:owner-ifx@pwg.org] On Behalf Of Gail Songer
Sent: Monday, February 03, 2003 1:14 PM
To: Rick Seeler
Cc: ifx@pwg.org
Subject: RE: IFX> Sender URI Stamp
Importance: High
Rick,
On a fax document, the date/time and ID of the sending machine are part of the
transmitted image; added to the image by the sender.
In keeping with current fax, I would think that we still want this information
as part of the image. So I guess I think that answer is "no, the information in
the dictionary is not quite enough". If the doc is printed and the soft copy
discarded then this information is lost.
The digital signature does validate the data from the originating sender, but
what if the receiving user decides to try to re-fax what he just got? Do we
replace the signature and the URI stamp?
Gail
-----Original Message-----
From: Rick Seeler [mailto:rseeler@adobe.com]
Sent: Monday, February 03, 2003 12:50 PM
To: Gail Songer
Cc: ifx@pwg.org
Subject: RE: IFX> Sender URI Stamp
Gail,
A digital Signature gives you a tamper-proof way to time-stamp a document, but
besides that...
What about using the information in the "Document Information Dictionary" (See
Table 9.2 in the PDF Reference 1.4)? This dictionary is already part of the
PDF/is spec. and should be all that is needed. Of course, it's not tamper proof
unless the document is also digitally signed.
Is this what you were looking for?
-Rick
-----Original Message-----
From: owner-ifx@pwg.org [mailto:owner-ifx@pwg.org] On Behalf Of Gail Songer
Sent: Monday, February 03, 2003 12:11 PM
To: ifx@pwg.org
Subject: IFX> Sender URI Stamp
Hi,
It's occurred to me that with PDF we have level of portability that we didn't
have before. However the IFX spec requires that the sender add the URI of the
sender:
The Sender MUST place the Sender's URI, i.e., the value of the
"sender-uri" attribute (see section 8.3), along with the date
and time, in one of the following places, DEPENDING ON
IMPLEMENTATION:
1. On a cover page automatically generated by the Sender that is sent before
the rest of the document.
2. Merged with the first page of the document.
3. At the top of every page of the sent Document.
The Sender MAY include additional data (Sending User, Receiver
identity, etc.). As for regular FAX, it is RECOMMENDED that
this information be represented as bit map data, so that it is
more difficult for it to be modified before it gets to the
Receiver.
My first thought was to add an optional field to the PDF that indicated where
the Stamp was located. If the doc was resent, then the second sender could
replace the Stamp with its own stamp. But if the doc was digitally signed then
either the Signature would be lost or invalidated.
Anything thoughts on how we should handle this?
Gail
This archive was generated by hypermail 2b29 : Mon Feb 03 2003 - 17:00:16 EST