Q: Are my files safe on Cloud storage, or should I encrypt them before I upload them?
A: The files are safe from most criminals, and internal corporate spy’s.
But not safe from from the cloud support staff, nor government troublemakers. All these folks have keys to read your data.
To block everyone, you need to aes256 encrypt individual files or folders with something like veracrypt (https://www.veracrypt.fr/en/Home.html) or Virtru (https://virtru.com).
Original post https://www.quora.com/Are-my-files-safe-on-OneDrive-or-should-I-encrypt-them-before-I-upload-them/answer/Marc-Mintz-4