PDF is the most popularly used format for sending and receiving files on the internet. To prevent an unauthorized person from reusing or misusing the PDF documents, people, especially these PDF files creators, are likely to set passwords to protect them. However, due to bad memory or some other unpredictable reasons, they may lose PDF password and be rejected to get access to their PDF files.

How To Open A Password Protected PDF File When You Lost Or Forgot PDF Password

So, if you forgot PDF password, how can you retrieve forgotten PDF file password and enter the file again? Luckily, there is a way you can open password protected PDF file after you forgot the password.


How to Open PDF Files If You Forgot PDF Password

You can use PDF password recovery software programs, such as SmartKey PDF Password Recovery, Wondershare PDF Password Remover, etc.

SmartKey PDF Password Recovery Tool

It is a useful PDF file password recovery tool which is designed to find forgotten PDF document password. Using a brute force technique, this PDF password recovery tool, which owns three password attack types, will uncover your PDF document password QUICKLY and EFFICIENTLY. Here is a detailed description on how to decrypt PDF file step by step.


Step 1: Download and Install PDF Password Recovery Tool

Open your web browser and go to ‘SmartKey’ official website. Download SmartKey PDF password recovery software and install it on your computer.

Step 2: Import PDF Document that You Forgot Password for

Download and Install PDF Password Recovery Tool

Launch the program. In the main interface, click “Open” button to add PDF file into the PDF Password Recovery window. This program supports multilingual PDF files.

Step 3: Select One Password Attack Type

Select One Password Attack Type

  • There are three kinds of attack types for documents: brute-force attack, brute-force with mask attack and dictionary attack.
  • Each of them has their own features. If you know part of the password, you can select brute-force with mask attack and click on “Options” to set the length and some tips of the password. This can speed up the password recovery process.
  • Likewise, you can set parameters for each attack.

Step 4: Recover Forgotten PDF Password

Recover Forgotten PDF Password

  • Click “Start” button to begin the recovery. It will start the process of trying to find the PDF document password.
  • Check the progress indicator to view the progress of the password attack. This could take several minutes.
  • The specific time depends on the password length. The longer the password, the more time it will take.
  • When SmartKey PDF Password Recovery finds the password, a screen will pop up with the password listed there.
  • Copy and paste it to open your PDF file.


 Wondershare PDF Password Remover

Wondershare PDF Password Remover is a professional Password Recovery tool, with which you can crack/unlock protected PDF without a password. The process is quite simple with this tool to remove password from protected PDF.

Step 1: Import Password Protected PDF to Program

Import Password Protected PDF to Program

  • Launch Wondershare PDF Password Remover. You can see there is an option called “Add Files” in the top left the corner.
  • Click on it and choose the password protected PDF file you want to unlock.
  • You can also add multiple files based on your needs, as it supports batch conversion.

Step 2: Select Output Folder for Opening Protected PDF (Optional)

Select Output Folder for Opening Protected PDF

  • As you can see, there are 2 options in the “Output Folder” at the bottom left – “Save target file(s) in source folder” and “Customize”.
  • By selecting “Save target file(s) in source folder”, the files will be saved in the default folder of the program. By selecting “Customize”, you can choose the output folder you prefer.
  • Then click on “Start”. In just a few seconds, you’ll successfully remove PDF protections, where you can open password protected PDF files without any hassle.

Step 3: Open Password Protected PDF

Open Password Protected PDF

After you remove password from protected PDF, you can open it in any PDF tool, which you can edit, copy or paste, based on your needs.

How to Crack password-protected PDF Files?

A secure PDF file enforces copyright laws with features to prevent reproduction or distribution by other users. There are basically two types of PDF protection – One is password based encryption and the otheruser accessibility restriction.

A) User accessibility restriction is that the original PDF creator can either restrict opening the PDF file itself or he can restrict others from modifying, printing or copying text and graphics from the PDF file.

Simply put, “user” password protection and “owner” password protection. First one prevents opening a document without knowing the password. The second protects information in a document from being printed, copied or edited.

(i) When you can view the pdf but there are Copying or Printing Restrictions

Removing this type of “protection” is easiest because the security entirely depends on the pdf reader to honor those limitations. You can always use custom pdf readers which do not honor the restrictions. There is also a number of tools available online which can remove such restrictions on the file.

If you need to edit or copy text from a PDF file, but don’t have access from the owner, follow these steps to unlock the PDF file.

  • Open the document in Acrobat Reader and capture the PDF page as an image using any free screen capture software.
  • If you want to copy just a portion of text from some PDF page, use a screen capture tool with OCR features.
  • Alternatively, you can use commercial solutions like Advanced PDF Password Recovery or PDF Password Remover.
  • These utilities may not recover the password for you – they’ll just remove the restrictions from the password protected file.

(ii) When there are Document Opening Restrictions.

This is a very tricky case and there’s no straight-forward solution to read PDF documents that are password-protected at the Open level.

Advanced PDF Password Recovery Professional edition from ElcomSoft is a recommended option. When (if) the password is found, the program shows it, as well as the number of passwords which have been tested, and the program speed.

When there are Document Opening Restrictions

The software will use methods like Brute Force, Key Search and Dictionary Attack to guess the password. They will try to use all possible character combinations as the password and so the process might take hours or even days and would really depend on your computer’s processing power.

B) Password based encryption, however, is not easy to remove. The contents of the file are encrypted and you would need the correct password to decrypt the contents. There is no bypassing.

There are weaknesses in the pdf password protection specification. The Older version of pdf used a weak 40/128 bit RC4 algorithm. Newer versions use the stronger Rijndael (AES actually) with larger key lengths. Hence cracking pdf passwords by brute force, dictionary attacks may be feasible for old versions of pdf, but definitely not for the newer versions. Unless you have some information about the password, such as the number of characters, starting/ending etc you are out of luck.


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