Issue/Question
Is it possible to make changes to a signed PDF document?
Environment
- Adobe Acrobat
- Adobe Reader
Resolution
The purpose of cryptographic digital signatures is to prevent files from being changed after they are signed. Any change to the file invalidates the signature.
If the PDF file is locked when it was signed, changes cannot be made to the file. There are programs and online services that claim to unlock locked PDF files. The IT Division recommends against using unlocking software and services, because they may harm your computer or expose your personal information to third-parties. Even if the document is unlocked, any change to the file will void the digital signature.
If the PDF file was not locked when it was signed, Acrobat may allow you to make changes. However, any changes to the file will invalidate the digital signature.