The way we always did was to add a custom driver and insert a few lines of gpg calls.

So while yes, there's no "native support" it's definitely not hard to add.

While this is just a random google result[1] as I don't have access to the aforementioned snippet, you'll get the idea I hope.

[1]: http://www.iniy.org/?p=151

I've been using backup2l with a custom driver that just calls "tar | gpg". I wouldn't flag it as "lacking". Backup2l can be used with any archiver.

If duplicity had an option to chose a backup ancestor, you could use backup2l with duplicity.

backup2l is strikingly simple and very effective at managing restores from it's incremental backup hierarchy.

In one of my tests (more than 2 years ago), the backup efficiency of daily, 3-level hierarchical tar (such as backup2l) vs Duplicity for a 1 year period was only 15% greater yet giving much more redundancy in case of failure.

If you consider how simple archives are and can be restored in case of problems, it's almost a no brainer.