I mean, the fourth amendment says a lot about warrants, both in the abstract and in regard to probable cause. You're right that there are warrantless exception

I mean, the fourth amendment says a lot about warrants, both in the abstract and in regard to probable cause. You're right that there are warrantless exceptions (most notably, Horton, which clarified the plain view doctrine), but I'm not aware of any case law that compels a third-party to break encryption/build a backdoor in order to satisfy a warrant. That was the genesis of the Apple v. FBI case. Even Lavabit, the rulings were largely procedural and didn't get to the merits of Lavabit's claims against the government's attempts to coerce a service provider into turning into a surveillance apparatus.