http://gpp6nwvsps43b3mfacsh433uroo6uyjvvpr6tgj4jh4n5ngxt7rqbvid.onion/posts/storing-a-sensitive-document.html
Once you have concluded that your sensitive document must be stored off-premises, the next question is where. For some threat models, a commercial cloud provider such as Amazon AWS or Microsoft Azure would suffice. For other threat models, you would want to store your document in a private data center. And in still other situations, you might be looking at more exotic solutions, such as server providers who accept Bitcoin or who operate out of a nuclear bunker in Sweden.