Leonard,
But I actually changed just one of them. Seems to be that the other
tree count as modified too.
Of course is valid, signatures are still valid. But in my workflow I
need to know if all signatures are over the same values.
So, I was facing to look at each significant field in every revision
and check they value the same. I think I am able to do that. Unless I
am doing this wrong and there is a better way you can suggest me.
Thanks you very much.
Emilio
On Thu, Jul 23, 2009 at 3:38 PM, Leonard Rosenthol<[email protected]> wrote:
> Actually FOUR fields were modified between the revisions (according to
> Acrobat 9's modification list).
>
> And under what criteria do you consider it "spoiled"? Under many workflows,
> it is perfectly valid, since the second signature "resigned" the original
> plus the changes.
>
> However, if you wish to determine what has changed between revisions you need
> to look at the LOW LEVEL OBJECTS in the PDF file to see what objects exist in
> the update table and whether they are significant to you or not.
>
> Leonard
>
>
> -----Original Message-----
> From: Emilio Oca [mailto:[email protected]]
> Sent: Thursday, July 23, 2009 12:18 PM
> To: Post all your questions about iText here
> Subject: Re: [iText-questions] How to check differences between signed
> revisions
>
> Hi,
>
> Attached is a pdf with two signatures.
> One of the fields had it's contents modified between the first and the second
> signing How can I get to know and reject this as a spoiled document?
> Shall I get each revision and check every signed field? Can you enlighten me
> how?
>
> Best.
>
> Emilio
>
> On Wed, Jul 22, 2009 at 3:43 PM, Emilio Oca<[email protected]> wrote:
>> Yes, I meant that each signature covers the hole present document at
>> the signing moment.
>> To check that I use:
>>
>> PdfReader reader = new PdfReader( acroFiledsf.extractRevision(
>> revision ) );
>> boolean covers =
>> reader.getAcroFields().signatureCoversWholeDocument( revision );
>> reader.close();
>>
>> where revision is each signature associated revision.
>>
>> Sorry for asking, but shall I sent the document here?
>>
>> Best.
>>
>> Emilio
>>
>> On Wed, Jul 22, 2009 at 3:25 PM, Leonard Rosenthol<[email protected]> wrote:
>>> Sure you can.
>>>
>>> The first signature covers the original document while the second covers
>>> the original PLUS the additions. Assuming no other changes other than
>>> signing, both should be valid.
>>>
>>> If the first signature is a certifying signature, then you could
>>> potentially have other operations as well between signatures and they could
>>> both still be valid.
>>>
>>> Leonard
>>>
>>> -----Original Message-----
>>> From: Paulo Soares [mailto:[email protected]]
>>> Sent: Wednesday, July 22, 2009 2:06 PM
>>> To: Post all your questions about iText here
>>> Subject: Re: [iText-questions] How to check differences between
>>> signed revisions
>>>
>>> You can't have two valid signatures covering the whole document. Show
>>> us the PDF.
>>>
>>> Paulo
>>>
>>> ----- Original Message -----
>>> From: "Emilio Oca" <[email protected]>
>>> To: <[email protected]>
>>> Sent: Wednesday, July 22, 2009 6:41 PM
>>> Subject: [iText-questions] How to check differences between signed
>>> revisions
>>>
>>>
>>> Could someone explain me (or point me where to find) how to check if
>>> differents signatures on a document where made over differents
>>> contents?
>>> I am trying to check if a document containing acrofields signed for
>>> first time where later modified when signed again.
>>> Both signatures seems to be valid and cover the hole document.
>>>
>>> Best
>>>
>>> Emilio
>>>
>>>
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