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pdf encryption assertion failure
https://forum.pdfsharp.net/viewtopic.php?f=3&t=3414
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Author:  berrywhite [ Fri Aug 05, 2016 6:47 pm ]
Post subject:  pdf encryption assertion failure

I encountered an assertion failure when I tried to encrypt some specific pdf file (sorry it's 500KiB with only one page and cannot be uploaded)

and I am using the pdf sharp source code (PDFsharp-1_50-beta3b.zip) to build my own PdfSharp.dll,

I noticed that this pdf triggers the following code in PdfDocument.cs

// HACK: Remove XRefTrailer
if (_trailer is PdfCrossReferenceStream) ----------------> condition got met
_trailer = new PdfTrailer((PdfCrossReferenceStream)_trailer);

Although I have no idea why we need this hack, it seems the failure can be fixed by adding the following codes:

----------------
iref = trailer.Elements.GetReference(Keys.Encrypt);
if (iref != null)
Elements.SetReference(Keys.Encrypt, trailer.Elements.GetReference(Keys.Encrypt));
----------------
in the function "public PdfTrailer(PdfCrossReferenceStream trailer)" in PdfTrailer.cs

Please help to confirm, thx

Author:  TH-Soft [ Fri Aug 05, 2016 7:35 pm ]
Post subject:  Re: pdf encryption assertion failure

Hi!

My proposed fix for this issue can be found here:
http://stackoverflow.com/a/38593235/1015447

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