I compared the xdp of the file filled in with iText and the file filled in
with Adobe Reader. There are two differences:
With Adobe:
<form xmlns="http://www.xfa.org/schema/xfa-form/2.8/";
checksum="q2aZZ1c6RqxVGD3ZxOOFJIOhtN4=">
<subform name="form1">
<instanceManager name="_form"/>
<subform name="form">
<area name="Body">
<field access="readOnly" name="EmployeeName">
<value override="1"/>
</field>
<field access="readOnly" name="Address">
<value override="1"/>
</field>
<field access="readOnly" name="StateProv">
<value override="1"/>
</field>
<field access="readOnly" name="HomePhone">
<value override="1"/>
</field>
<field access="readOnly" name="CellPhone">
<value override="1"/>
</field>
<field access="readOnly" name="SignatureField1"/>
</area>
<field name="TextField1">
<value override="1"/>
</field>
</subform>
<pageSet>
<pageArea name="Page1"/>
</pageSet>
</subform>
</form>
with iText:
<form xmlns="http://www.xfa.org/schema/xfa-form/2.8/";
checksum="G3x6fZ508XKDw1SpO6DvjRZ3aQE=">
<subform name="form1">
<instanceManager name="_form"/>
<subform name="form">
<area name="Body">
<field access="readOnly" name="EmployeeName">
<value override="1"/>
</field>
<field access="readOnly" name="Address">
<value override="1"/>
</field>
<field access="readOnly" name="StateProv">
<value override="1"/>
</field>
<field access="readOnly" name="HomePhone">
<value override="1"/>
</field>
<field access="readOnly" name="CellPhone">
<value override="1"/>
</field>
<field access="readOnly" name="SignatureField1"/>
</area>
</subform>
<pageSet>
<pageArea name="Page1"/>
</pageSet>
</subform>
</form>
Notice that the checksum of the form is different (because of the next
change) and the Adobe form contains:
<field name="TextField1">
<value override="1"/>
</field>
which was added after I filled in this text field with Adobe. So, filling in
a text field, alters both the data section and add that field to the form
section.
I searched XFA specs 2.8 for <form xmlns="
http://www.xfa.org/schema/xfa-form/2.8/";>, I wanted to know how the checksum
is calculated and whether is used to validate the signature in any way, but
didn't find anything.
I should have found something though, according to Leonard's answer to this
post:
http://www.mail-archive.com/itext-questions@lists.sourceforge.net/msg49070.html
Any suggestions, please?
Thank you.
2011/5/5 Cosmin Ciuraru <cosmin.ciur...@gmail.com>
> Hello,
>
> While using the methods in my first post, in order to fill the fourth field
> in my form, I noticed, by exctracting the entire XFA structure (with
> templates, datasets, etc.), that, my datasets part had the following
> structure:
>
> <xfa:datasets xmlns:xfa="http://www.xfa.org/schema/xfa-data/1.0/";>
> <xfa:data>
> <xfa:datasets>
> <xfa:data>
> <xfa:form>
> ...
>
> So, the datasets and data tags were doubled. This, I suspected to generate
> the error message in Acrobat Reader (dataModel does not have a method
> 'clone') and went on to fix it.
>
> The behaviour, as much as I can tell was due to two reason:
> 1. The xml file that I imported had identation
> (tf.setOutputProperty(OutputKeys.INDENT,
> "yes"))
> 2. I got the itext source code, went into the com.itextpdf.text.pdf
> package, class XfaForm, method public void fillXfaForm(Node node) and
> changed the line 1154 from data.replaceChild(domDocument.importNode(node,
> true), data.getFirstChild()) to
> data.replaceChild(domDocument.importNode(node.getFirstChild().getFirstChild(),
> true), data.getFirstChild()).
> Though it may not be the best solution, it generates the xfa ok.
>
> So, after recompiling iText and running my tests again, Acrobat Reader
> doesn't display the error message anymore, but, the first signature, that of
> the user, becomes invalid. If I click the signature panel, it now shows the
> details and it says that I have modified all the fields in the form, thus
> invalidating the signature, although, I actually only modified field number
> four, which wasn't included in the collection of objects for the first
> signature.
>
> From what I read from XFA specs 3.1, I have this:
>
> "Unlike an XML digital signature, a PDF signature signs the XFA form
> exactly as it is currently expressed,
> rather than signing a normalized copy. This means that it is not possible
> to make even meaningless
> changes to the XFA form without voiding the signature. For example,
> changing a space to a tab in between
> an element tag and the following attribute name voids the signature, even
> though it does not change the
> meaning of the XML."
>
> So, if you could point out whether is it possible to modify a field in a
> xfa form, without invalidating the signature, that, obviously, wasn't
> applied to that field?
>
> Thank you!
>
>
>
> 2011/5/3 Leonard Rosenthol <lrose...@adobe.com>
>
>> Then modifying the entire XFA data block after document signing is a bad
>> thing…
>>
>>
>>
>> *From:* Cosmin Ciuraru [mailto:cosmin.ciur...@gmail.com]
>> *Sent:* Tuesday, May 03, 2011 7:57 AM
>> *To:* Post all your questions about iText here
>> *Subject:* Re: [iText-questions] iText fill XFA Form and Digital signing
>>
>>
>>
>> According to this classification:
>>
>> * *
>>
>> *
>> http://help.adobe.com/en_US/livecycle/9.0/designerHelp/index.htm?content=000628.html
>> *
>>
>>
>>
>> I use document signatures. The users just click on the signature field to
>> sign the document and send it to me afterwards. There is no submit/email
>> button.
>>
>>
>>
>> Thank you!
>>
>>
>>
>>
>>
>>
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>>
>> iText(R) is a registered trademark of 1T3XT BVBA.
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>> http://itextpdf.com/themes/keywords.php
>>
>
>
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The most intuitive, comprehensive, and cost-effective network
management toolset available today. Delivers lowest initial
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