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Posted to dev@pdfbox.apache.org by "Michael Klink (JIRA)" <ji...@apache.org> on 2017/12/18 11:51:00 UTC
[jira] [Commented] (PDFBOX-3198) Visible Signature N2 layer
[ https://issues.apache.org/jira/browse/PDFBOX-3198?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16294871#comment-16294871 ]
Michael Klink commented on PDFBOX-3198:
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Unfortunately I have not spotted this issue or PDFBOX-3817 ("Signature form names not standard") before, so my warning most likely is a bit too late.
{panel}
*The PDF standard does not define any specific names for child XObjects of signature appearances, nor does it specify the concept of layers. What you try to emulate merely is Adobe's style in creating them.*
The Adobe's style includes these names and layers because in very early Adobe Acrobat/Reader versions the determined validity of a signature was displayed by showing additional layers provided by the PDF, a concept Adobe deprecated in Adobe Acrobat 6 .
There is no need to adapt the Adobe style unless you want to create signature fields with these deprecated additional layers.
{panel}
For a discussion of the deprecation of this layer concept, cf. [this stack overflow answer|https://stackoverflow.com/a/40391641/1729265].
> Visible Signature N2 layer
> --------------------------
>
> Key: PDFBOX-3198
> URL: https://issues.apache.org/jira/browse/PDFBOX-3198
> Project: PDFBox
> Issue Type: New Feature
> Components: Signing
> Affects Versions: 1.8.11
> Reporter: Frank Cornelis
> Priority: Minor
> Attachments: PDFBOX-3198-visible-signature.zip, PDFBOX-3198-work-5.5.2017.zip, helloworld_signed.pdf, pdfbox-n2-2.patch, signed.pdf
>
>
> The patch adds N2 layer support to visible signatures.
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