Pypdf 6 Encryption And Form Filling

6. Encryption and Form Filling

6. Encryption and Form Filling

"""
PDF encryption, decryption, and form handling.
"""
from pypdf import PdfReader, PdfWriter
from pathlib import Path
from typing import Dict, Optional, List

def encrypt_pdf(
    input_path: str,
    output_path: str,
    user_password: str,
    owner_password: Optional[str] = None,
    permissions: Optional[Dict[str, bool]] = None
) -> None:
    """Encrypt PDF with password protection.

    Args:
        input_path: Source PDF file
        output_path: Destination file
        user_password: Password to open the document
        owner_password: Password for full access (defaults to user_password)
        permissions: Dict of permission flags (print, modify, copy, etc.)
    """
    reader = PdfReader(input_path)
    writer = PdfWriter()

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

    # Copy metadata if exists
    if reader.metadata:
        writer.add_metadata(reader.metadata)

    # Default permissions (restrictive)
    default_permissions = {
        'print': True,
        'modify': False,
        'copy': False,
        'annotations': True,
        'forms': True,
        'extract': False,
        'assemble': False,
        'print_high_quality': True
    }

    if permissions:
        default_permissions.update(permissions)

    # Encrypt
    owner_pwd = owner_password or user_password
    writer.encrypt(
        user_password=user_password,
        owner_password=owner_pwd,
        permissions_flag=-1  # All permissions by default
    )

    writer.write(output_path)
    print(f"Encrypted PDF saved to: {output_path}")


def decrypt_pdf(
    input_path: str,
    output_path: str,
    password: str
) -> bool:
    """Decrypt a password-protected PDF.

    Args:
        input_path: Encrypted PDF file
        output_path: Destination file (unencrypted)
        password: Password to decrypt

    Returns:
        True if successful, False otherwise
    """
    try:
        reader = PdfReader(input_path)

        if reader.is_encrypted:
            if not reader.decrypt(password):
                print("Incorrect password")
                return False

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

        if reader.metadata:
            writer.add_metadata(reader.metadata)

        writer.write(output_path)
        print(f"Decrypted PDF saved to: {output_path}")
        return True

    except Exception as e:
        print(f"Decryption failed: {e}")
        return False


def get_form_fields(input_path: str) -> Dict[str, Dict]:
    """Get all form fields from a PDF."""
    reader = PdfReader(input_path)
    fields = {}

    if reader.get_fields():
        for name, field in reader.get_fields().items():
            field_type = field.get('/FT', '')
            value = field.get('/V', '')

            fields[name] = {
                'type': str(field_type),
                'value': str(value) if value else '',
                'field': field
            }

    return fields


def fill_pdf_form(
    input_path: str,
    output_path: str,
    field_values: Dict[str, str],
    flatten: bool = False
) -> None:
    """Fill PDF form fields with values.

    Args:
        input_path: Source PDF with form fields
        output_path: Destination file
        field_values: Dictionary of field names and values
        flatten: If True, make form fields uneditable
    """
    reader = PdfReader(input_path)
    writer = PdfWriter()

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

    # Update form fields
    writer.update_page_form_field_values(
        writer.pages[0] if writer.pages else None,
        field_values
    )

    if flatten:
        # Note: Full flatten support may require additional processing
        for page in writer.pages:
            if '/Annots' in page:
                del page['/Annots']

    writer.write(output_path)
    print(f"Form filled and saved to: {output_path}")


def list_form_fields_report(input_path: str) -> str:
    """Generate a report of all form fields in a PDF."""
    fields = get_form_fields(input_path)

    if not fields:
        return "No form fields found in this PDF."

    report = ["PDF Form Fields Report", "=" * 40, ""]

    for name, info in fields.items():
        report.append(f"Field: {name}")
        report.append(f"  Type: {info['type']}")
        report.append(f"  Current Value: {info['value'] or '(empty)'}")
        report.append("")

    report.append(f"Total fields: {len(fields)}")

    return "\n".join(report)


# Example usage
# encrypt_pdf('document.pdf', 'encrypted.pdf', 'mypassword')
# decrypt_pdf('encrypted.pdf', 'decrypted.pdf', 'mypassword')
#
# fields = get_form_fields('form.pdf')
# fill_pdf_form('form.pdf', 'filled_form.pdf', {
#     'name': 'John Doe',
#     'date': '2026-01-17',

*Content truncated — see parent skill for full reference.*