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Except when the watermark is right in the middle of the page and harms reading flow. I had the case a few months ago very frustrating. The PDF was encrypted, I

Except when the watermark is right in the middle of the page and harms reading flow. I had the case a few months ago very frustrating. The PDF was encrypted, I couldn't remove the watermark.

SSLy 5y ago
There are open source apps that ignore PDF "encryption"
- newaccount74 5y ago
  qpdf --decrypt infile.pdf outfile.pdf
- criddell 5y ago
  Where do they get the key from?
  - oauea 5y ago
    No key needed, else you'd need one for viewing the content too.
    - criddell 5y ago
      You do need a key just to view. Acrobat 9 and above uses AES with a 256-bit key. I think it's all built on Adobe's Digital Editions technology.
- jmnicolas 5y ago
  Since I wanted to read it asap, I didn't invest too much time trying to defeat it but if you have something reliable I'm all ears for next time. From what I understand Adobe Acrobat might have done the job, but it's an expensive software and I refuse to run cracks anymore.
  - Isthatablackgsd 5y ago
    Calibre with DeDRM plugin can remove the encryption and DRM. Done this few years ago for my undergrad, it works well. Just import the PDF to Calibre and Calibre will handles it from there (as long you have the DeDRM plugin). It depends on the encryption being used. If it is coming from Abode Digital Edition, then DeDRM plugin need your credential to decrypt it and convert the file without encryption. It needs your credential since ADE ties the encryption to your credential, so it need that to get the key to decrypt it. First setup will be a while but once it is properly setup, it will takes seconds to decrypt the encrypted/DRMed PDFs. Even you can print the file without worrying if it will be in garbled mess.
akvadrako 5y ago
Watermarks don't even have to be visible. They could do things that survive re-encoding but are too subtle to see. For example adding a few slightly off color pixels to random letters on the page.
- jmnicolas 5y ago
  In this case I think the goal is to discourage publishing the PDF since your email will be visible to all the people that downloads it. I wouldn't mind them protecting their work if it didn't harm readability and if the report was worth the money I paid (but it's another problem).

Except when the watermark is right in the middle of the page and harms reading flow. I had the case a few months ago very frustrating. The PDF was encrypted, I couldn't remove the watermark.

SSLy 5y ago

There are open source apps that ignore PDF "encryption"

newaccount74 5y ago
qpdf --decrypt infile.pdf outfile.pdf
criddell 5y ago
Where do they get the key from?
- oauea 5y ago
  No key needed, else you'd need one for viewing the content too.
  - criddell 5y ago
    You do need a key just to view. Acrobat 9 and above uses AES with a 256-bit key. I think it's all built on Adobe's Digital Editions technology.
jmnicolas 5y ago
Since I wanted to read it asap, I didn't invest too much time trying to defeat it but if you have something reliable I'm all ears for next time. From what I understand Adobe Acrobat might have done the job, but it's an expensive software and I refuse to run cracks anymore.
- Isthatablackgsd 5y ago
  Calibre with DeDRM plugin can remove the encryption and DRM. Done this few years ago for my undergrad, it works well. Just import the PDF to Calibre and Calibre will handles it from there (as long you have the DeDRM plugin). It depends on the encryption being used. If it is coming from Abode Digital Edition, then DeDRM plugin need your credential to decrypt it and convert the file without encryption. It needs your credential since ADE ties the encryption to your credential, so it need that to get the key to decrypt it. First setup will be a while but once it is properly setup, it will takes seconds to decrypt the encrypted/DRMed PDFs. Even you can print the file without worrying if it will be in garbled mess.

akvadrako 5y ago

Watermarks don't even have to be visible. They could do things that survive re-encoding but are too subtle to see. For example adding a few slightly off color pixels to random letters on the page.

jmnicolas 5y ago
In this case I think the goal is to discourage publishing the PDF since your email will be visible to all the people that downloads it. I wouldn't mind them protecting their work if it didn't harm readability and if the report was worth the money I paid (but it's another problem).