detect pdf tampering

Question

Hi, the web app I am currently working on generates a PDF file and sends to user who will use this PDF as a certificate.

My question is, how to make sure that this PDF file is impossible to be tampered by the user?

Thanks,

Answer 1

You can't stop someone altering the binary form of a file they hold since they can use a byte editor to change contents. You can however ensure that the PDF tampering is detected. Look at the Digital Signature facilities of PDF or consider doing a checksum/digest yourself on the PDF and keeping that with the PDF. At any time in future you can run the checksum algorithm again to see if it has been modified.

Answer 2

We implemented a certificate creation workflow for a scholastic company using Apago's PDF Constructor and PDF Enhancer products. PDF Constructor takes XML as input and creates PDF for output. Enhancer optimizes the certificates and applies security and digital signatures.