Signature Integrity Checks

Aspose.PDF for Python via .NET provides the PdfFileSignature facade for validating signed PDF documents. After a file has been signed, you can use it to check whether the signature applies to the complete document and whether the signed content is still valid.

This example demonstrates two common integrity checks:

1. Check whether a signature covers the whole document.
2. Validate the integrity of the signed PDF content.

Check whether a signature covers the whole document

Use covers_whole_document() when you need to confirm that the signature applies to the complete PDF and not only to part of its content. The example reads the first available signature name and checks its coverage.

import aspose.pdf.facades as pdf_facades
import sys
from os import path


def check_signature_coverage(infile):
    pdf_signature = create_pdf_file_signature(infile)
    try:
        sign_name = require_signature_name(pdf_signature)
        covers_document = pdf_signature.covers_whole_document(sign_name)
        print(f"Signature '{sign_name}' covers the whole document: {covers_document}")
    finally:
        pdf_signature.close()

Validate document integrity

Use verify_signed() to confirm that the signed document content has not been altered after the signature was applied. This method helps verify whether the document remains valid for the selected signature.

import aspose.pdf.facades as pdf_facades
import sys
from os import path


def validate_document_integrity(infile):
    pdf_signature = create_pdf_file_signature(infile)
    try:
        sign_name = require_signature_name(pdf_signature)
        is_valid = pdf_signature.verify_signed(sign_name)
        print(f"Document integrity for '{sign_name}' is valid: {is_valid}")
    finally:
        pdf_signature.close()