A Technique for the Detection of PDF Tampering or Forgery

TL;DR

This paper introduces a new method for detecting tampering in PDF documents by analyzing their file page objects, capable of identifying changes to text, images, or metadata.

Contribution

The paper presents a novel technique that detects PDF tampering by examining file page objects, overcoming limitations of existing hash and watermarking methods.

Findings

Effective detection of text modifications.

Identification of image alterations.

Detection of metadata changes.

Abstract

Tampering or forgery of digital documents has become widespread, most commonly through altering images without any malicious intent such as enhancing the overall appearance of the image. However, there are occasions when tampering of digital documents can have negative consequences, such as financial fraud and reputational damage. Tampering can occur through altering a digital document's text or editing an image's pixels. Many techniques have been developed to detect whether changes have been made to a document. Most of these techniques rely on generating hashes or watermarking the document. These techniques, however, have limitations in that they cannot detect alterations to portable document format (PDF) signatures or other non-visual aspects, such as metadata. This paper presents a new technique that can be used to detect tampering within a PDF document by utilizing the PDF document's file page objects. The technique employs a prototype that can detect changes to a PDF document, such as changes made to the text, images, or metadata of the said file.