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https://issues.apache.org/jira/browse/PDFBOX-3853?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16076331#comment-16076331
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ryuukei commented on PDFBOX-3853:
---------------------------------
Yes, in my client code I'm not just checking page 1, just scanning and looking
for signatures it there is any. All right, I see your concern. But...from the
code logic, I don't think this patch will produce bug. Anyhow current code
updating the catalog for visible signatures, if there is risk for invisible
signature there should be the same risk for visible signature.
Btw, I got the attached test file [test1.pdf] from issue PDFBOX-3114, which
produce invalid signature. I signed with 2 visible signatures on page1 and
page2, then one invisible signature, then another visible signatures on page1
and 5th visible signature on page 2. Acrobat reader validated all signatures as
valid.
> Invisible signature's page catalog tree is not updated
> ------------------------------------------------------
>
> Key: PDFBOX-3853
> URL: https://issues.apache.org/jira/browse/PDFBOX-3853
> Project: PDFBox
> Issue Type: Bug
> Components: Signing
> Affects Versions: 2.0.6
> Reporter: ryuukei
> Priority: Minor
> Labels: signature
> Attachments: PDDocument.patch
>
>
> According latest Acrobat PDF 1.7 speficication:
> http://www.adobe.com/content/dam/Adobe/en/devnet/acrobat/pdfs/pdf_reference_1-7.pdf
> Page 695, section [Signature Fields]:
> * quote 1:
> The field type ( FT ) is Sig , and the field value
> ( V ) is a signature dictionary containing the signature and specifying
> various at-
> tributes of the signature field.
> * quote 2:
> Like any other field, a signature field may actually be described by a widget
> anno-
> tation dictionary containing entries pertaining to an annotation as well as a
> field
> (see “Widget Annotations” on page 640). The annotation rectangle ( Rect ) in
> such
> a dictionary gives the position of the field on its page. Signature fields
> that are not
> intended to be visible should have an annotation rectangle that has zero
> height
> and width.
> All in all, invisible signature also should be as a Signature Field, which is
> one type of Annotation, thus the page catalog tree should be updated as well.
> For fixing this improvement issue, in the class PDDocument.java L351~L353,
> instead of terminating the process after [prepareVisibleSignature] by return,
> continue with later on annotation update process would be better.
> Personally I'm using itext-rups to analyse the pdf catalog structure, after
> applying the patch, the signature present in the catalog tree
> pages/page/annot/sig correctly.
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