If you’re using a cloud storage, i.e. storing files and other data on someone else’s computer, then you can use a few different tools to encrypt your files. You can take a look at either VeraCrypt or Cryptomator as Cyrus pointed out. There are a few key differences between VC and CM that are worth pointing out.
- VeraCrypt volumes have a set amount of space, which you can define upon creation of a VeraCrypt volume, for example 3 GB.
- VeraCrypt let’s you choose the algorithm(s).
- VeraCrypt supports keyfiles and hardware keys, such as Yubikey or Onlykey.
- Cryptomator has flexible storage. Instead of defining the size of a volume upfront, it’ll adjust the volume size depending on the contents, which is much more convenient.
- VeraCrypt allows you to create a hidden volume. In the rare event of extortion, you can give out the password to the visible volume instead of the hidden one.
In the end it doesn’t matter which one you use, but I do recommend encrypting any files before uploading them to a cloud storage provider. Cloud storage providers may retain your files even after deletion for an unspecified time, you never really know whether your data is gone, and they can also access your data.
If you are more paranoid, I’d suggest using VeraCrypt with both a password and a keyfile or a hardware key. There is an edge case where they may hold onto your data indefinitely or share it with some government agency. They may not be able to hack their way into your container right now, but they may be able to do so in the future. If you use a keyfile or a hardware key, it’ll make it nearly impossible to break into your encrypted volume. Only issue here is that you need to store your keyfile safely and separately or ensure you keep your hardware key safe and backed up.
My suggestion is to give both options a try and see which one you prefer.