How to add blank page to pdf digital signature using java?

Question

I want to insert a blank page at the end of a digital PDF using the itext library . and my confusion about adding pages will invalidate existing signatures? Thanks.

Answer 1

To answer Jory in context, check out the Adobe white paper, Digital Signatures, Changes, and Improvements for Adobe Acrobat 9 , especially its Allowed and Denied Changes section. Here, Adobe explains the permitted changes (as seen from Acrobat 9 and above) that can be made to a certified or signed document without canceling the signatures applied to the document.

Allowed Actions for Certified Documents

Certified unchanged.

• Allowed
  • No changes allowed
• Disallowed
  • Digital signature
  • Supply form field values
  • Add or edit annotations
  • Adding Form Fields
  • Change page content

Certified with filling out a form and digitally signed

• Allowed
  • Supply form field values
  • Digital signature
• Disallowed
  • Add or edit annotations
  • Adding Form Fields
  • Change page content

Certified by annotations, form filling and digital signatures, allowed

• Allowed
  • Add or edit annotations
  • Supply form field values
  • Digital signature
• Disallowed
  • Adding Form Fields
  • Change page content

Allowed actions for signed but uncertified documents

• Allowed
  • Adding signature fields (see Restrictions when adding signature fields to signed but not certified documents).
  • Add or edit annotations
  • Supply form field values
  • Digital signature
• Disallowed
  • Adding form fields other than signature fields
  • Change page content

As you can see, “Changing page content” is always in the “Forbidden” category. Since adding a page changes the contents of the page - subsequently there is at least a white page where nothing had happened before, this is not allowed.

(Despite the fact that this is not explicitly mentioned here, page template templates are most likely also allowed when filling out forms, as this complies with the PDF standard, see ISO 32000-1 , section 12.8.2.2.2. But the use of such page templates will require that the document be specially prepared before signing, and your question sounds like the documents are already signed without any such preparation ...)

PS: Obviously, even these allowed changes must be added in the add mode, for example, incremental updates. Everything else will break the signature forever. In some cases, see Answer.

Answer 2

Yes it will. The signature is based on the content that is signed, so if you change the content, the signature is no longer valid.

If you subscribe, you can simply sign the document again.

If the pages you add are empty, it doesn't matter.