I made a php backup that compress, split and encrypt the file with AES 256 through openssl, then upload it to remote backup storage and verify that the file transfered correctly. It work quite well in our case. You can also take a look at GPG, it's the opensource for PGP. It also does encryption quite well.
I personally like the openssl route because it's all command line and I can automate everything using Cron on our 10.5 server.