Well, some would say that's already suggested in the Universal Declaration of Human Rights, Article 12. "No one shall be subjected to arbitrary interference with his privacy, family, home or correspondence [...]" That's from 1948 already... But of course when implemented into law, it gets softened up and exceptions get added for when it's "[...] necessary in a democratic society in the interests of national security, public safety or the economic well-being of the country, for the prevention of disorder or crime, for the protection of health or morals, or for the protection of the rights and freedoms of others." ( European Convention on Human Rights).
But I think you're right. We need awareness for the importance of privacy. And exact standards on how severe exactly these other things need to be to warrant breaking privacy. And I think we need a distinction between targeted spying on people, and mass surveillance. And we might want to lobby for a law to outlaw mass surveillance and be done with it.
(For Germans: https://www.freiheit.org/de/deutschland/gibt-es-ein-recht-auf-verschluesselung )