Have you tried duplicity [0]? It encrypts the archives using GnuPG, uses two separate keys - one for encryption, the other for signing, and can store the backups using a multitude of protocols [1]: > Currently local file storage, scp/ssh, ftp, rsync, HSI, WebDAV, Tahoe-LAFS, and Amazon S3 are supported, and others shouldn't be difficult to add.

It is libre software and cross-platform. A number of front-ends address the issue of ease-of-use.

[0]: http://duplicity.nongnu.org/ [1]: http://duplicity.nongnu.org/features.html