If you use a Mac, you can create an encrypted HFS disk overlaid on top of another filesystem that TimeMachine can then back up to. Depending on the size of the disk and frequency of the backup, you can keep snapshots that are as long as a year old. You can then take nightly backups of the disk (which is literally just a folder) and store it on a cloud provider or any remote storage. I've been doing this for the past year or so and it's been flawless.