CODEWITHSUNDEEP
pdfsignatureacrobat
Carlos Daniel
Carlos Daniel

Reputation: 13

PDF Acrobat Verifying Signature

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

Upvotes: 1

Views: 1113

Answers (1)

mkl
mkl

Reputation: 96039

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

Signature Panel screen shot

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":

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:

Page 1 dictionary

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.

Upvotes: 1

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