As I wrote, there are 6 revisions to the PDF. Each time you signed it, you
created one.
The reason there are only five signatures, however, is because when you
"resigned' one of the fields, iText REPLACED the entire field (and it's
associated signature) so that Acrobat/Reader NEVER SEE the older signature.
The fact is, this is perfectly valid – since you allowed form fill & sign in
your certification.
HOWEVER, the signature fields are marked "locked", which means that iText
should NOT allow a "resign" over that field. So iText DOES have a bug here (at
least based on my reading of the PDF). Of course, that wouldn't prevent some
other tool from doing the same – but again, it's perfectly legal.
Leonard
From: Rouan van Dalen <[email protected]<mailto:[email protected]>>
Reply-To: Rouan van Dalen <[email protected]<mailto:[email protected]>>
Date: Mon, 24 Oct 2011 08:28:24 -0700
To: Leonard Rosenthol <[email protected]<mailto:[email protected]>>
Subject: Re: [iText-questions] Resigning digital signatures in PDF not
invalidating other signatures
Here is the PDF I use.
The Signature_MainCustomer field is always signed first (so I expect it to be
revision 2, because of the certification signature). After signing all the
other fields, I then resign the
Signature_MainCustomer signature field. You will notice that the
Signature_MainCustomer signature field is now revision 5 in the supplied PDF.
Regards
________________________________
From: Leonard Rosenthol <[email protected]<mailto:[email protected]>>
To: Rouan van Dalen <[email protected]<mailto:[email protected]>>; Post
here
<[email protected]<mailto:[email protected]>>
Sent: Monday, 24 October 2011, 17:18
Subject: Re: [iText-questions] Resigning digital signatures in PDF not
invalidating other signatures
Let's see a PDF…
Without it, we're clueless (as the crystal ball broke last week :(
From: Rouan van Dalen <[email protected]<mailto:[email protected]>>
Reply-To: Rouan van Dalen <[email protected]<mailto:[email protected]>>,
Post here
<[email protected]<mailto:[email protected]>>
Date: Mon, 24 Oct 2011 07:59:54 -0700
To: Post here
<[email protected]<mailto:[email protected]>>
Subject: Re: [iText-questions] Resigning digital signatures in PDF not
invalidating other signatures
I have now confirmed the behaviour. I only get up to 5 signatures: 1
certification and 4 approval signatures. I can sign the same field 5 times,
the resulting PDF will never
have more than 5 signatures.
I am using ITextSharp 5.1.1 to add the signatures. Might this be a bug in the
ITextSharp lib?
I also expected to see at least more revisions or invalidated signatures, but
none of that is happening.
Regards
________________________________
From: Leonard Rosenthol <[email protected]<mailto:[email protected]>>
To: Rouan van Dalen <[email protected]<mailto:[email protected]>>
Sent: Monday, 24 October 2011, 16:37
Subject: Re: [iText-questions] Resigning digital signatures in PDF not
invalidating other signatures
If you are signing again, then it's just ADDING to the PDF – it's not REPLACING
the existing signature, which is why nothing is broken.
Look in the Signature panel in Acrobat/Reader, and you will see that there are
now 6 signatures ( 1 Cert + 4 Fields + 1 "resign") instead of 5 as I think you
are expecting.
Leonard
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