> I assume you mean that decryption happens on the server and you provide the server with the password each time you need to access something.
Yes, this is what I meant.
> In that case the server provider has your data the instant you submit the password to the server. The password will exist at least in server memory, and your unencrypted files will also exist at least in server memory.
Yes, that's true. So the unencrypted data only exists in server memory, while you're logged in. Not perfect, for sure, but perhaps good enough. Protects against e.g. server theft. Doesn't protect against hostile server operators at all, of course.