Hoping someone can help. As the title suggests I need some advice in securely locking a PDF after it has been signed.
Thanks in advance
In the world of signatures it is of no importance that the file can be edited. Because this invalidates the signatures, which is all that matters: it proves the file is not authentic.
Consider: even if Word couldn't open it, someone could copy/paste.
If they couldn't copy/paste they could print and scan.
If they couldn't print, then could RETYPE it.
You could encrypt the file first, but set the permissions to allow for signing. After that you can sign the encrypted file (you just can't encrypt a signed file). As long as you get the order of operations correct (encrypt first, sign second) you will end up at the same place you are trying to get to.