It's possible to change the security so the contents of the page can only be changed by providing the password.
However, it's still possible to remove/add pages from the document. In Adobe Acrobat you can disallow "document assembly" so the document in itself can't be manipulated.

Is something like this possible in (a future version of) Prince?

We use prince to create certificates with in them some extra pages containing detailed background information. We don't want anyone to replace the background information essentially manipulating the certificate.

We will investigate this issue.

In the latest build of Prince we have added an --allow-assembly option as an exception to --disallow-modify (and --allow-copy-for-accessibility as an exception to --disallow-copy), I hope this helps!

Great! Thanks!