> I have yet to regret trusting people to keep documents as private as I request. Keeping shared content private is always to a large extend a matter of social

> I have yet to regret trusting people to keep documents as private as I request. Keeping shared content private is always to a large extend a matter of social trust. No technological solution can fully enforce permissions that you have chosen. Even if you require Google login and explicitly specify a group of people that can access a document, an allowed person can still copy-paste the content and share it with a larger group, or simply tell others about the content.