Non-standard /DefaultValue key in the /Pages dictionary

Aspose.PDF Product Family
1

I have a PDF document that when examining its metadata has this object:

2 0 obj
<< /Type /Pages
   /Count 4
   /Kids [3 0 R 22 0 R 25 0 R 28 0 R]
   /DefaultValue (GykqNSk/dAoeHHo8NSh6dBQfDnpobnRodGo=)
>>
endobj

Apparently, /DefaultValue is non-standard for /Pages and when I decode the string

python -c "import base64; print(''.join(chr(b ^ 0x5A) for b in base64.b64decode('GykqNSk/dAoeHHo8NSh6dBQfDnpobnRodGo=')))"

It returns

Aspose.PDF for .NET 24.2.0.

Is this some sort of trial version artifact or was it likely inserted by the creator of the document?

Thanks.

2

@o90

The presence of the /DefaultValue key in the /Pages dictionary of your PDF document is non-standard and not typically found in standard PDF specifications. The decoded value indicating “Aspose.PDF for .NET 24.2.0” suggests it may have been inserted by the software that created or modified the PDF.

This could be a remnant from a trial version of Aspose.PDF or a custom implementation by the document’s creator. If the document functions correctly and meets your needs, it may not be a concern. However, if you are experiencing issues with the PDF, I recommend investigating further or recreating the document using a different method.

To proceed, please let me know if you are facing any specific issues with this PDF or if you require further assistance. I’m here to help!

3

This could be a remnant from a trial version of Aspose.PDF

It would be really helpful if you could confirm this is true.

4

@o90

The trial version of Aspose.PDF for .NET (Without license) restricts you from processing more than 4 elements of any collection e.g. Pages, Annotations, etc. It also leaves/adds a watermark in the final output mentioning “Evaluation” usage. These restrictions may result in what you are seeing in document structure. You can however get a free 30-days temporary license and use it to remove the above restrictions and check if you still notice this in metadata.

5

Thank you for the reply. I was given these documents and noticed this artifact. My my hypothesis is that they were modified (post-processed) with Aspose .NET using a trial version, and then removed the watermark (or whatever sort of identifiable mark is imposed on a trial version). All the documents are 4 pages long, which seems odd and is in line with the trial versions 4-page restriction. My question is does Aspose leave a bit-masked breadcrumb in the event there is watermark tampering? I couldn’t find anything in the documentation about this, which actually makes sense, if you advertised this in documentation, everyone would know about it.

6

@o90

To confirm, yes this mark is from Aspose.PDF and we are planning to remove it. This matter is currently under consideration and we will let you know as soon as we have some updates about its implementation.

7

Thank you again for the response. To be clear, I am indifferent to the presence of the mark, I was given documents and am simply analyzing metadata. I am only interested in the mechanism that produces it. If you could provide any information about that, that would be really helpful. Thanks.

8

@o90

Do you mean how Aspose.PDF API produces this mark in metadata internally? OR what event triggers API to add this mark in the PDF metadata?

9

I understand that the code mechanism (how Aspose.PDF produces this mark internally) might not be something that you’d like to reveal, and I understand that. I am more interested in the second thing (what event triggers the API to add this mark). As in, for example:

“There are only 3 ways this mark can show up, 1) …, 2) …, 3) …”

Thanks.

10

@o90

We need to investigate and gather related information. We will get back to you on it soon. Please spare us little time.

1 Like
11

@o90

This information is added in the PDF documents in any case. We used this flag to store some technical information related to Aspose.PDF. However, we have decided to remove it as it is causing issue for our users. A task as PDFNET-60620 has been logged in our issue tracking system to carry out this operation. We will let you know as soon as the task is completed. Please be patient and spare us some time.