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Source of checksum within the xfa form element

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Source of checksum within the xfa form element

nandre
When you save a xfa document in adobe, they add a checksum attribute to the form element. This checksum appears to be a SHA1 digest of the file. However, it's unclear as to what is actually fed to the hash. Does anyone have any idea as to how this is generated? I believe this value is needed for adobe to validate what's actually in the form xml. I found a topic that asked the same question, but it was never resolved.

http://itext-general.2136553.n4.nabble.com/Xfa-signature-td2172306.html

Thanks!
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Re: Source of checksum within the xfa form element

iText mailing list
On 12/11/2014 15:13 PM, nandre wrote:
> When you save a xfa document in adobe, they add a checksum attribute to the
> form element. This checksum appears to be a SHA1 digest of the file.
> However, it's unclear as to what is actually fed to the hash. Does anyone
> have any idea as to how this is generated? I believe this value is needed
> for adobe to validate what's actually in the form xml. I found a topic that
> asked the same question, but it was never resolved.

The problem with this issue is that the checksum isn't documented
anywhere in the XFA specification. Only Adobe knows how it's calculated.
We have tried to create the hash in many different ways using different
XML streams. Unfortunately, we didn't have any success...

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Re: Source of checksum within the xfa form element

Leonard Rosenthol-3
Everything is documented - there is nothing private.   If you can’t find
it, I will be happy to obtain the details.

Leonard




On 12/14/14, 2:41 PM, "iText mailing list" <[hidden email]> wrote:

>On 12/11/2014 15:13 PM, nandre wrote:
>> When you save a xfa document in adobe, they add a checksum attribute to
>>the
>> form element. This checksum appears to be a SHA1 digest of the file.
>> However, it's unclear as to what is actually fed to the hash. Does
>>anyone
>> have any idea as to how this is generated? I believe this value is
>>needed
>> for adobe to validate what's actually in the form xml. I found a topic
>>that
>> asked the same question, but it was never resolved.
>
>The problem with this issue is that the checksum isn't documented
>anywhere in the XFA specification. Only Adobe knows how it's calculated.
>We have tried to create the hash in many different ways using different
>XML streams. Unfortunately, we didn't have any success...
>
>--------------------------------------------------------------------------
>----
>Download BIRT iHub F-Type - The Free Enterprise-Grade BIRT Server
>from Actuate! Instantly Supercharge Your Business Reports and Dashboards
>with Interactivity, Sharing, Native Excel Exports, App Integration & more
>Get technology previously reserved for billion-dollar corporations, FREE
>http://pubads.g.doubleclick.net/gampad/clk?id=164703151&iu=/4140/ostg.clkt
>rk
>_______________________________________________
>iText-questions mailing list
>[hidden email]
>https://lists.sourceforge.net/lists/listinfo/itext-questions
>
>iText(R) is a registered trademark of 1T3XT BVBA.
>Many questions posted to this list can (and will) be answered with a
>reference to the iText book: http://www.itextpdf.com/book/
>Please check the keywords list before you ask for examples:
>http://itextpdf.com/themes/keywords.php
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Re: Source of checksum within the xfa form element

iText mailing list
On 12/15/2014 0:07 AM, Leonard Rosenthol wrote:
> Everything is documented - there is nothing private.   If you can’t find
> it, I will be happy to obtain the details.

I can't find it...

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Re: Source of checksum within the xfa form element

nandre
In reply to this post by Leonard Rosenthol-3
I know this is a late reply, but do you think you could pin point where the spec describes the source of the checksum that's placed within <form> root? I still can't seem to find it.

Thanks
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