Nothing that hard. When I had a technically similar need (for non-shady purposes unrelated to recruiting) I found easy installable free GUI software for Windows that worked just fine with a simple Google search. No specialist expertise needed.
Yes, most consumer software does respect what you say. But it’s easy for a minimally motivated consumer to obtain and use software which doesn’t.
However, the context we were discussing was neither a consumer nor a forensic security researcher, but a recruiter trying to do shady things with a resume. I don't expect them to be a specialist, but I do expect them to be able either to get the kind of software I just described with a security stripping feature, or else to have access to third-party software specifically targeting the recruiter market that will do the shady things - including to digitally signed PDFs like yours - without them having to know how it works.
Yes, most consumer software does respect what you say. But it’s easy for a minimally motivated consumer to obtain and use software which doesn’t.
However, the context we were discussing was neither a consumer nor a forensic security researcher, but a recruiter trying to do shady things with a resume. I don't expect them to be a specialist, but I do expect them to be able either to get the kind of software I just described with a security stripping feature, or else to have access to third-party software specifically targeting the recruiter market that will do the shady things - including to digitally signed PDFs like yours - without them having to know how it works.