PDF encryption is sort of silly. If you really wanted to grab the text, you can screen capture each page and then OCR it. So clearly the true intention of the encryption is to deter the 99% of the users who wouldn’t go to such lengths to try to copy text.
Recently, I received a PDF of a text document that I needed as plain text (it was a database DDL commands of a system I was analyzing). For some reason the author had encryption turned on so that I couldn’t copy and paste the text, and I was a bit impatient and didn’t want to wait for the author to send me the original text file. However, this PDF still allowed printing.
Since I had Acrobat, I tried to print the file into a PDF to remove the encryption. Nope. Acrobat is smart enough to keep you from doing that. But then I installed the Windows "Generic Text" printer driver and set it to print to a file. By printing my "encrypted" PDF to the Generic Text printer, the text of the whole document was nicely saved for me. After removing the page breaks and the margin I had my original database text document.
The punchline is: If you don’t want users to easily copy text from your encrypted PDF files, you
not only need to turn off the text copy capability, but also the print
capability. Why? Because it can easily be foiled using the Windows Generic Text
printer driver.
