I actually wrote an article 8 months ago on how I do it (https://thatgeoguy.ca/blog/2013/12/26/encrypted-backups-in-debian/ https://thatgeoguy.ca/blog/2013/12/2

I actually wrote an article 8 months ago on how I do it (https://thatgeoguy.ca/blog/2013/12/26/encrypted-backups-in-debian/ https://thatgeoguy.ca/blog/2013/12/26/encrypted-backups-in-d...). Granted, this is for personal use, and really relies on cron / rsync to work well. Let me know if you have any questions about how I got it to work (for the most part, the biggest issue I see you encountering is encrypting drives on OSX).