How to Crack PDF Files Passwords in Python?

Let's say you have a PDF file that is locked or protected with a password, and you wish to crack that password with a Python program. So how to crack PDF file passwords in Python?

Well, there are two approaches you can follow to crack the password of a PDF using Python code. In the first approach, you can create a key for the corresponding encryption technique that encrypted your PDF.

Doing so, however, is hard because it is near to impossible to revert back an encrypting technique and retrieve a correct key because these days, to encrypt a file, the application can use more than a single encryption technique.

Another approach you can use to crack PDF files passwords in Python is the " Brute Force Approach, " in which you have a list of thousands or millions of vulnerable and strong passwords.

With the help of Python, you create a program that automates the process of passing the listed passwords to open the locked pdf file.

How to Crack PDF Files Passwords in Python?

In this Python program, we will be using the Brute Force approach to crack the password of a pdf file. The password for the file is 1a2b3c . Before discussing the Python program, let's install the required dependencies.

Installing and Setting Up Dependencies

1) The Python pikepdf Library

The pikepdf library is an open-source Python library that is used to handle and manipulate PDF files. For this tutorial, we will be using this Python library to open the locked pdf file that is protected with a password. To install the pikepdf library for your Python environment, run the following Python pip install command on your terminal or command prompt:

pip install pikepdf

Python Program to Crack PDF Files Passwords in Python

First, let's import the pikepdf library to our Python script.

import pikepdf

passwords_filename = "passwords_list.txt"
locked_pdf_file = "my_locked.pdf"

#load passwords file
with open(passwords_filename) as file:
    
    passwords_list = file.readlines()
    total_passwords = len(passwords_list)

    for index,password in enumerate(passwords_list):
        
        #try if password is correct
        try:
            with pikepdf.open(locked_pdf_file, password = password.strip()) as pdf_file:
                print("\n++++++++++++++++++++++SUCCESS+++++++++++++++")
                print("Success---------- File is Unlocked and the password is: ", password)
                break
        #if password fail
        except:
            print("\n=====================")
            print(f"Trying Password {password} --- Fail!!!!")
            scanning =  (index/total_passwords)*100
            print("Scanning passwords complete:", round(scanning, 2))
            continue

Now put all the code together and execute.

# Python program to crack PDF password using Brute Force

import pikepdf

passwords_filename = "passwords_list.txt"

locked_pdf_file = "my_locked.pdf"

#load passwords file
with open(passwords_filename) as file:
    
    passwords_list = file.readlines()
    total_passwords = len(passwords_list)

    for index,password in enumerate(passwords_list):
        
        #try if password is correct
        try:
            with pikepdf.open(locked_pdf_file, password = password.strip()) as pdf_file:
                print("\n++++++++++++++++++++++SUCCESS+++++++++++++++")
                print("Success---------- File is Unlocked and the password is: ", password)
                break
        #if password fail
        except:
            print("\n=====================")
            print(f"Trying Password {password} --- Fail!!!!")
            scanning =  (index/total_passwords)*100
            print("Scanning passwords complete:", round(scanning, 2))
            continue

Output

Trying Password blondie
--- Fail!!!!
Scanning passwords complete: 0.15
=====================
Trying Password bigs
--- Fail!!!!
Scanning passwords complete: 0.15

=====================
Trying Password 272727
--- Fail!!!!
Scanning passwords complete: 0.15

++++++++++++++++++++++SUCCESS+++++++++++++++
Success---------- File is Unlocked and the password is: 1a2b3c

When you execute the program it might take 50 to 55 minutes to completely scan the passwords_list.txt file passwords with the locked pdf file.

As you can see from the output that our pdf file password was 1a2b3c. The script is only able to find it out because the password is very weak and available in the list of passwords_list.txt file.

If you have a pdf file that has a unique password, then this program will not be able to crack the password of your PDF file.

Conclusion

In this Python tutorial, you learned " How to Crack a PDF file in Python? " The approach we followed in this tutorial was Brute Force, in which we tried to open a password-protected PDF file using a file having 10 million passwords.

If you have a locked pdf file and you have no idea about its password, then you can use this python program to crack that pdf file. However, it is not guaranteed that this program will crack your PDF file. Nonetheless, if the PDF file has a weak password, then this program might crack it.

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