PDF Acrobat Verifying Signature

Question

I am verifying a PDF with two signatures (Adobe Acrobat), both valid. One of them has a text say "cambio(s) varios" (my Adobe Acrobat is in Spanish) translating to Enghish "change(s) various", my question is I don´t know what it mean. Signatures are valid and the PDF is correct.

Thanks in advance

Answer 1

First of all, to outline what this is about, the Adobe Acrobat Reader signature panel looks like this for the document at hand

and the question is about the

1 Miscellaneous Change(s)

in-between.

According to Adobe Documentation

In a number of documents Adobe enumerates possible modification entries and characterizes "Miscellaneous Change(s)" like this:

Miscellaneous: Some changes which occur in memory or cannot be explicitly listed are labelled miscellaneous.

(e.g. in "Digital Signatures Workflow Guide for the Adobe® Acrobat Family of Products")

Now this documentation obviously is no help at all...

According to Adobe Acrobat

Fortunately Adobe Acrobat can be asked to show "Document Integrity Properties":

(Adobe Acrobat 9.5 output on "Signature Properties" - "Legal" - "View Document Integrity Properties...")

I assume it is this detail that makes Adobe Reader warn about miscellaneous changes.

In Your Document

Looking for a transfer function use in your document one quickly indeed finds one in a ExtGState resource of page 1:

The TR entry in that graphics state dictionary sets the transfer function here.

Interestingly the transfer function used is the Identity function! I assume that in most normal use cases setting the transfer function to Identity changes nothing...

What to Do

Thus, I would propose you change your original document creation to not include transfer functions, in particular not Identity transfer functions. Alternatively pre-process your documents before applying the first signature and remove such functions.