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kjumaa
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Digital Signature and Annotation Appearance Stream

Jul 31, 2012 3:53 AM

Hello,

 

I've noticed that adding an annotation on a pdf without specifying an appearance stream ( AP dictionary ) for that annotation, and then signing the document,

will cause Acrobat to report that the document is Signed and all signatures are valid, but with Annotations Modified message under the signed revision in the signature panel.

So is that behavior by acrobat, while appearance stream entry is optional in annotations ?

 
Replies
  • Currently Being Moderated
    Jul 31, 2012 5:58 AM   in reply to kjumaa

    Ah – because that appearance stream is then added by Acrobat at the time of rendering, which means the file has been modified!

     

    Appearances are optional, EXCEPT in this case – for security reasons.

     
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  • Currently Being Moderated
    Jul 31, 2012 6:12 AM   in reply to kjumaa

    I guess it depends on where you come from.  For many, adding a digital signature and/or timestamp would be more difficult than drawing an ink annotation.

     

    But yes, if you are going to sign, then you have to apply the appearance.    You can add a fake appearance, but then the user will see the fake appearance and not the real thing – which is probably not what you want.

     
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  • Currently Being Moderated
    Jul 31, 2012 6:57 AM   in reply to kjumaa

    The way to build the appearance stream is to read all the properties and then use them to build the appearance stream.

     

    The Acrobat SDK already provides APIs for doing all this.

     
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  • Currently Being Moderated
    Aug 17, 2012 7:43 AM   in reply to kjumaa

    its becouse the document was changed maybe...

     
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