Create an unsigned copy of the digitally signed pdf (which prevents copying, annotating, etc), using pypdf

remove_pdf_sign.py

"""
To use this script:

1. Install dependencies:
```bash
pip install pypdf
```

2. Run it with your input file path and desired output path.

This approach works by:
- Creating a new PDF document containing all content pages
- Removing permission flags that might restrict text selection/copying
- Bypassing signature validation through reconstruction of the PDF structure
"""

from pypdf import PdfReader, PdfWriter

def remove_signature(input_path, output_path):
    # Create PDF reader and writer objects
    reader = PdfReader(input_path)
    writer = PdfWriter()

    # Copy all pages to new writer
    for page in reader.pages:
        writer.add_page(page)

    # Remove any encryption/digital signature restrictions
    if len(reader.root_object):  # Check if root object has security info
        writer._root_object.pop("/Perms", None)
        
    # Save the modified PDF
    with open(output_path, "wb") as f:
        writer.write(f)

# Usage example
remove_signature("mathematical-modeling-in-life-sciences-an-introduction-9798724872027_compress.pdf", "output_accessible.pdf")