BACKUP can create and restore encrypted save sets.

    Using encryption may be required due to your data archival security
    policy or for transferring files via non-secure channels.
    Additional CPU time is required to process encrypted files.

    See the /ENCRYPT qualifier for details.

    Note that when simultaneously using both compression and encryption
    to create a save set, the data is encrypted first.  This means
    that very little data compression can then be accomplished.