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When I encrypt a PDF using pdftk under Ubuntu 22.04, I cannot decrypt it using Adobe Acrobat under Windows.

Following instructions here, I encrypt a PDF using pdftk:

pdftk input.pdf output output.pdf owner_pw 1234567890 user_pw 1234567890 allow printing

However pdftk returns this error:

Error: The user and owner passwords are the same.
   PDF Viewers interpret this to mean your PDF has
   no owner password, so they must be different.
   Or, supply no owner password to pdftk if this is
   what you desire.

So I try:

pdftk input.pdf output output.pdf user_pw 1234567890 allow printing

This produces an output.pdf file that appears to be encrypted and that I can open with the user_pw in Ubuntu, but when I try to open it in Acrobat on Windows it says that the password is incorrect.

Is there something I need to be doing differently when encrypting it to be able to read it with Acrobat on Windows?

1 Answers1

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My answer is to use qpdf instead. This worked for me, plus it uses 256-bit AES instead of 128-bit RC-4 (?), so it should be more secure:

qpdf --encrypt [userpass] [ownerpass] 256 -- input.pdf output.pdf