Are you trying to print a PDF file that you received via email but are unable to complete the operation because you are asked to enter a password that you do not know? You obviously stumbled upon an owner password protected document. But no, don't be scared! Behind this very strange term there is actually an extremely simple concept to understand: give me two minutes and I'll explain it to you.
PDF documents can be protected with two different types of passwords: the owner password which protects files against printing or modification and the user password which prevents the opening of documents by those who do not know the exact keyword. The owner password can be easily bypassed, it only takes a few seconds. The user password, on the other hand, is much more difficult to overcome. The only way to find out is to perform a brute force attack on the document by trying all possible combinations of characters until you find the right one - an operation that can take hours, if not days, to complete successfully.
Having clarified this fundamental concept, we can also see how to remove PDF security using some solutions available for free on the net. I assure you that in one way or another you will be able to unlock your PDF, view its content and print it. All you need is a little luck and some free time. Good luck!
Remove PDF Owner Password
If you need to unblock printing or editing a PDF, you can safely rely on one of the solutions listed below, all free.
The first software I recommend you try is called QPDF. It's free, open source, and runs on all major software platforms: Windows, macOS, and Linux. In my tests it proved extremely effective, but it has a "flaw" that could discourage its use by less experienced users: it does not have a graphical interface, it must be used via the command line.
If you are not "afraid" of this limit and want to try your hand at using QPDF, connect to this SourceForge page and download the program by clicking on the item qpdf-6.0.0-bin-mingw64.zip if you are using a 64-bit version of Windows or on voice qpdf-6.0.0-bin-mingw32.zip if you are using a 32-bit version of Windows.
When the download is complete, open thezip archive you just downloaded to your PC, extract the contents to any folder and launch QPDF via the Command Prompt. To do this, hold down the key Shift on the keyboard, right click on the folder bin present in the folder where you extracted QPDF and select the item Open command window here from the menu that opens. This will open the Windows Command Prompt directing it directly to the folder that contains QPDF.
Now, give the command qpdf --decrypt input.pdf output.pdf where instead of input.pdf e output.pdf you have to type the full path of the PDF to be unlocked and the output file to be obtained (i.e. the unlocked PDF). If you want to do this first, to get the full path of a file, you can directly drag it into the Command Prompt window. Within a few seconds you will get an unlocked version of the PDF in the folder you indicated as the output.
I use a Poppy? In this case, to download and install QPDF you have to rely on Homebrew: a free and open source package manager that allows you to install various types of software from the Terminal.
To install Homebrew first and then QPDF on your Mac, you need to open the terminal (I puoi trovare nella cartella Other Launchpad) and type the following commands.
- / usr / bin / ruby -e "$ (curl -fsSL https://raw.githubusercontent.com/Homebrew/install/master/install)" to install Homebrew (you will need to type your account password on macOS).
- brew install qpdf to install QPDF.
When the installation is complete, open the macOS Terminal and give the command qpdf --decrypt input.pdf output.pdf where instead of input.pdf e output.pdf you have to type the paths of the input and output files. To do this first, you can get the full path of a file by simply dragging it into the Terminal window.
Portable PDF Unlocker (Windows)
If QPDF seems a little too difficult to use, you can turn to Portable PDF Unlocker, a free software for Windows that allows you to remove the protection against printing and editing from PDF files by simply dragging them into its main window. It is compatible with all versions of the Microsoft operating system and does not require installations to function.
To download Portable PDF Unlocker on your PC, connect to the SourceForge website and click on the item Portable PDF Unlocker x86 x64 2.1.7z. A download complete, apri il 7z package you just downloaded to your PC using 7-Zip, WinRAR or any other software that can extract 7z files and copy Portable PDF Unlocker files to a folder of your choice. Then start the executable Portable PDF Unlocker.exe and drag the PDF you want to unlock into the window that opens.
Within seconds you will find an unlocked version of the PDF (with the suffix unpw at the end of the name) in the original folder of the document.
Have no way to download and / or install a program to remove the owner password from your PDFs? In this case, you can contact gods online services for editing PDF files, which, among their many qualities, also have the ability to remove owner passwords from documents.
As for privacy, all the most famous online services claim to delete the files that upload to their servers within a few hours (usually 1 day), but from my point of view it is better to be wary and turn to this kind of solutions only if the documents to be processed do not contain sensitive data, such as credit card numbers, personal data, etc. If you need to operate on files that contain sensitive information, it is better to opt for offline and possibly open source solutions (therefore whose behavior can be thoroughly verified).
That said, if you have no way of downloading new software to your PC, I recommend you give it a try iLovePDF: an online service that allows you to convert and edit PDFs directly from your browser. It's free, you can use it without registration.
To use iLovePDF, connect to the service using this link, drag the PDF to unlock into the browser window and press the button Unlock PDF, bottom right.
The unlocked PDF file will be instantly downloaded to your computer, ready to be viewed, edited and printed with any software suitable for the purpose. Happy?
Remove PDF User Password
The task, as already said, becomes more difficult when you want Remove PDF Protection to a document to which the user password has been applied. One of the few free applications capable of effectively attacking files of this type (with the brute force technique) is PDFCrack which is available for Windows, macOS and Linux. Unfortunately the software does not have a graphical interface, it works as a command line, but it is not as complicated to use as you might think. Just learn the few commands needed to use it.
To download PDFCrack on your PC, connect to the program's website and click on the item Download located in the right sidebar. So open the zip archive that contains the software and extract the contents into any folder.
At this point, right click on the folder where you extracted PDFCrack and select the item Open command window here from the context menu to call up the Command Prompt automatically directing it to the program folder.
Now type the command pdfcrack [document.pdf] replacing [document.pdf] with the path and name of the document to be unlocked, press the key Submit on your computer keyboard and let the software work.
At the end of the attack, during which PDFCrack will try all possible combinations of characters until it finds the right password, the message will appear in the Command Prompt window found user-password followed by the password you must use to open the PDF.
If you use a Mac, you can download PDFCrack by connecting to this website and clicking on the link next to the item Looking for the latest version? (up).
Once the download is complete, open the package tar.gz just downloaded, extract the contents to a folder of your choice and compile the program by typing these two commands in the terminal macOS (you find it in the Other from the launchpad).
- cd [PDFCrack path] where instead of [PDFCrack path] you have to type the path where you previously extracted the application files.
- make -f makefile
At this point, open a new Terminal window and issue the following command for Remove PDF Protection.
[path to PDFCrack] / pdfcrack -u [path and name of the PDF to unlock].
Caution: I remind you that unlocking documents that you are not authorized to view or modify can be a crime. I do not take any responsibility for the use that you will make of the indications in this guide.