Don’t expect your cloud-saved data to be private. An article posted by NBC News points out instances of routine scans, by cloud storage providers, of their clients data.
Apple — which declined to comment — and Microsoft, along with Verizon Online, state in their user agreements that they reserve the right to actively search stored files.
Some providers will scan your data, while some will not without a court order. If data security is a priority, either some research into how much your provider will pry would be in order, or you could avoid cloud based systems and opt for a private backup instead.