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According to Wikipedia, retrieved 16:24, 14 September 2011 (CEST), “Portable Document Format (PDF) is an open standard for document exchange. This file format created by Adobe Systems in 1993 is used for representing documents in a manner independent of application software, hardware, and operating systems.[2] Each PDF file encapsulates a complete description of a fixed-layout flat document, including the text, fonts, graphics, and other information needed to display it.”

Security and usage rights

A PDF file may be encrypted for security, or digitally signed for authentication.

Various usage rights, can be included, e.g.

  • The ability to edit
  • the ability to save a PDF document along with annoations or filled-in forms

There exist software for password removal both commercial and free, e.g. pdfcrack under Linux. It takes a long time to break if you don't have a clue what kind of password you used

sudo aptitude install pdfcrack

Example that would permutate assci letters starting at words of 5 letters.

pdfcrack -f test.pdf -n 4 -c abcdefghijklmnopqrstuvwxyz




  • Adobe Acrobat Reader
  • (Some) ebook tools and readers, e.g. calibre
  • Ghostview (?)
  • evince (PDF/PS viewer, default Ubuntu client ?)
  • xpdf-reader
web services
  • Adobe Acrobat Professional
  • pdfedit (Linux)
  • gpdftext (Linux, for writing e-books)
Password removal