How to Unblock a Protected PDF in Python

 

PDF encryption is commonly used to restrict editing, copying, or printing. In many enterprise workflows—legal documentation, invoice processing, automation pipelines—you may need to remove protection from a PDF file programmatically, provided you have the authorized password.

In this guide, you’ll learn how to:

• Detect whether a PDF is encrypted
• Ask the user for file input dynamically
• Prompt securely for a password
• Generate an unprotected copy
• Handle errors cleanly
• We will use the Python library pypdf, the maintained successor to PyPDF2.

Understanding PDF Protection Types

Before writing code, understand what “protected” means:

NOTE - ⚠ Always ensure you have legal rights to modify the document.

Step 1 — Install Required Library

pip install pypdf

Step 2 — Python Script (User Input Based)

Below is a production-safe CLI script.

from pypdf import PdfReader, PdfWriter
import os
import getpass

def unlock_pdf():
    # Ask user for input file
    input_path = input("Enter PDF file path: ").strip()

    if not os.path.exists(input_path):
        print("❌ File not found.")
        return

    # Output file name
    output_path = input("Enter output PDF file name (e.g., unlocked.pdf): ").strip()

    try:
        reader = PdfReader(input_path)

        # Check encryption
        if reader.is_encrypted:
            print("🔐 PDF is encrypted.")

            # Ask password securely
            password = getpass.getpass("Enter PDF password: ")

            if not reader.decrypt(password):
                print("❌ Wrong password.")
                return
            else:
                print("✅ Password accepted.")
        else:
            print("ℹ️ PDF is not encrypted, removing restrictions anyway.")

        # Write unlocked file
        writer = PdfWriter()

        for page in reader.pages:
            writer.add_page(page)

        with open(output_path, "wb") as f:
            writer.write(f)

        print(f"✅ Unlocked PDF saved as: {output_path}")

    except Exception as e:
        print("❌ Error:", str(e))


if __name__ == "__main__":
    unlock_pdf()

Code Breakdown (Technical Explanation)

1️⃣ PdfReader

Loads the PDF file into memory.

2️⃣ is_encrypted

Checks whether the PDF is protected.

3️⃣ decrypt(password)

Attempts decryption using user-provided password.

4️⃣ PdfWriter

Rewrites pages into a new file without restrictions.

Execution Flow

User provides file path

        ↓

Program checks encryption

        ↓

If encrypted → Ask password

        ↓

Decrypt → Copy pages

        ↓

Write new PDF (unprotected)

Security Considerations

As someone with a security background (especially if you're exploring automation or SecDevOps workflows), keep these points in mind:

• Never store plaintext passwords in logs
• Use getpass() for secure input
• Avoid automating password cracking
• Log only metadata, not document content
• If integrating into CI/CD pipelines:
• Use environment variables for password input
• Restrict file system access
• Validate file extensions

Final Thoughts

Automating PDF decryption in Python is straightforward when using the correct libraries and maintaining proper security practices. This approach is ideal for:

• IT automation workflows
• Enterprise document processing
• Backend document services
• Internal compliance tools

Disclaimer

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