Preliminary information
Prima di enter the live tutorial, walking to spiegare how to unlock a secure PDF, there is some preliminary information, in this regard, which it is my duty to provide you.
You need to know that passwords applied to PDFs are not all the same. The type of file in question, in fact, can be protected with two different types of passwords: one is the owner password, which prevents you from making changes or printing documents and is very easy to remove; the other is there user password which, on the other hand, totally prevents access to files and can only be discovered by brute-force attack, that is, by attempting all possible combinations of characters, and this operation can take a very long time.
How to unlock secure PDF for free
Having made the above clarifications, let's get to the point and find out, in detail, how to unlock a protected PDF using some programs to Windows, MacOS e Linux: the ones I will talk about in the next steps. They are tools completely free and, although on the surface it may seem the opposite, also quite simple to use.
QPDF (Windows / macOS / Linux)
The program that I recommend you to use to remove the owner password, ie the password against printing or document changes, is QPDF. It's free, open source, and available for Windows, macOS, and Linux. It works from the command line, does not have a graphical interface, but is equally simple to use.
To download the program on Windows, go to the QPDF download page on the SourceForge website and click on the button Download Latest Version, which is located at the top left.
Once the download is complete, extract theZIP archive obtained in a folder of your choice and start QPDF via the Command Prompt, directing it directly to the folder containing the program. If you don't know how to do it, proceed like this: Press and hold 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 give the menu that comes mostrato.
Once the Command Prompt window appears on the screen, type the string qpdf --decrypt input.pdf output.pdf (instead of input.pdf and output.pdf you must type the full path of the PDF to be unlocked and the output file to get, you can get the full path of a file by simply dragging it to the command line) and press the key Submit on the keyboard. After following these steps, you will get an unlocked version of the PDF in the folder you indicated for the output file.
Stai using MacOS, 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 using the terminal. That said, first of all open the Terminal, selecting the relevant one icon (Quella with the nether finest in the riga di codice) found in the folder Other of Launchpad.
Once the Terminal window appears on your desktop, to install Homebrew, enter the command / usr / bin / ruby -e "$ (curl -fsSL https://raw.githubusercontent.com/Homebrew/install/master/install)" , followed by pressing the key Submit on the keyboard and by entering the administration password of the Mac. Then, to install QPDF, type the command brew install qpdf, always followed by pressing the key Submit.
Once the installation procedure is complete, enter the command qpdf --decrypt input.pdf output.pdf in the Terminal (instead of input.pdf and output.pdf you must type the paths of the input and output files, I remind you that also in this case you can get the full path of a file by simply dragging it to the command line), press the key Submit on the Mac keyboard and you will get an unlocked version of the PDF document.
PDFCrack (Windows / macOS)
If your need is to unlock a user password protected PDF, I suggest you rely on PDFCrack: it is a free and open source program, available for Windows and macOS, which uses the system of brute-force attacks to make documents accessible. Even in this case, however, it is a resource that works exclusively from the command line.
To download it on Windows, visit the program website and click on the link Download(pdfcrack-xx.zip, xxk) located in the right sidebar.
Once the download is complete, open theZIP archive obtained, extract the contents in a folder of your choice and recall the Command Prompt, facendo click sul Start button (I cheer with the windows flag) located at the bottom left of the taskbartyping "Prompt" in the displayed search field and selecting the collegamento relevant from the menu.
Now that you see the Command Prompt window on the screen, enter the command CD "[PDFCrack folder]" (instead of [PDFCrack folder] you must enter the full path of the folder where you extracted PDFCrack) followed by pressing the key Submit on the keyboard. Then type the command pdfcrack "file.pdf" (instead of file.pdf you must enter the complete path and the name of the file to be decrypted), always pressing the key Submit.
After completing the steps above, PDFCrack will start attacking the document to find its password. When found, you will be shown the writing found user-password, together with the password needed to open the file.
Stai using MacOSinstead, to use the program, visit the page dedicated to it on the SourceForge website and click on the button Download Latest Version located at the top.
When the download is complete, open thetar.gz archive obtained and extract the contents into a folder of your choice. Next, call up the terminal, selecting theicon (Quella with the nether finest in the riga di codice) found in the folder Other of Launchpad and issue the command cd [PDFCrack folder] (instead of [PDFCrack folder] you must enter the complete path of the folder in which you extracted PDFCrack), followed by pressing the key Submit on the keyboard. Then type the make f Makefile command, always followed by pressing the key Submit.
After carrying out the steps in question, open a new Terminal window, type the command [PDFCrack folder] / pdfcrack -u "file.pdf" (instead of [PDFCrack folder] you must enter the complete path of the folder where you extracted PDFCrack and instead of file.pdf you have to enter the full path and the name of the file to be decrypted), press the key Submit on the keyboard and you will finally be able to view the document password.
How to unlock secure PDF online
If you do not want to download programs on your computer, I inform you that, to unlock a protected PDF, you can also intervene online, using special Web services, such as those I will talk about in the following steps, which are functional from any browser and operating system.
Online2PDF
Online2PDF is an online service dedicated exclusively to editing, converting and unlocking PDFs. In the latter case, if it is a user password, it is necessary to know the password of the PDF in order to create a “free” copy. It should also be noted that it has restrictions on uploading. The service, in fact, does not allow you to upload more than 20 files at a time, which must have a total weight not exceeding 100 MB. Regarding privacy, Online2PDF removes the files uploaded to its servers after processing.
To use the service, go to its home page, click on the button Select files and select the documents to be processed. Alternatively, drag and drop files directly into the browser window. Once uploaded, if you need to unlock a file protected from unauthorized access, click on the black button with the padlock that you see appear next to the name of the document, type the password used to protect the PDF in the appropriate field that is shown to you and click on the button Converted, below, in order to download an unlocked copy of the document.
If before downloading the document you want to intervene on the degree of compression, on the display, on the header and footer or on the layout, I inform you that you can do so by selecting the appropriate tabs located at the bottom, in correspondence with the Pref Renze, and intervening on the various items and on the various menus that appear. If, on the other hand, you want to rotate the pages, select them, reorder them or split the file, click in advance on the button with the page and / or on the one with the phobic that you find next to the name of the document.
App to unlock secure PDF
To conclude, I want to point out some Whatsapp which you can use on Android e iOS to unlock a secure PDF on the go. Put them to the test now, I'm sure they will satisfy you!
iLovePDF (Android / iOS)
The first among the useful apps for unlocking a PDF that I invite you to consider is iLovePDF: this is a free solution, available for Android and iOS, which, separately unlocking the PDF (allows you to remove only the owner password), allows you to perform various types of operations on the type of file in question. It is free, but offers in-app purchases to subscribe to the paid plan of the service (at a cost of 5,99 euros / month or 48,99 euros / year), which allows you to remove advertisements and take advantage of other features extra.
To download the app on Android, visit the relative section of the Play Store and click on the button Install. If, on the other hand, you are using iOS, access the relevant section of the App Store, tap the button Get, then that Install and authorize the download via Face ID, touch ID o password dell'ID Apple. In segito, avvia l'app, premendo sul bottone apri comparso sul display oppure selecting the relative icon which has been added to the home screen.
Once the main screen of the app is displayed, press the button Unlock, decide whether to get the PDF from the device, from Google Drive or from dropbox and select the document of your interest.
Then, tap on the button Unlock PDF appeared below and waits for the unlocking process to be started and completed. When you see the writing appear Completed! on the display, you can press the button Go to file, to access the unlocked version of your PDF. Easier than that?
PDF Utilities (Android)
Another app you can rely on to unlock owner password protected PDFs is PDF Utilities to Android. It is free, very simple to use and, in addition to fulfilling the purpose in question, it also allows you to edit documents by removing and adding pages.
To download the application on your device, visit the relevant section on the Play Store and tap the button Install. Next, launch PDF Utilities, by tapping the button apri comparso sul display oppure selecting the relative icon added in home screen.
Once the main application screen is displayed, press the button with the three lines horizontally located at the top left and, from the menu that opens, select the option Remove write-protection. Then press the button Select, grant app i permissions needed to access files on your device and select the PDF you are interested in taking action.
In Seguito, Premium Pulsating Home and wait for the app to process the document. When the process is complete, a new unprotected file will be generated, which will be automatically saved in the same location as the original one.
How to unlock secure PDF