How can I identify if someone is real or an Artificial Intelligence when conversing with them over the internet without invading their privacy and/or security?
Good question!

You should try to ask them a question that requires some ability to reason and that is also such that the answer cannot be found in any any possible training materials that the artificial intelligence could have been trained on. This kind of questions often cause an AI to simply start making things up.

Naturally you should also know the answer to the question yourself, otherwise you won't be able to tell whether the answer is an AI 'hallucination' or a real human answer!