Dont think that's possible, FlashBackup is a block level backup of the File System. Can't encrypt a block. Also dont think it will be worth much without the catalog information, so its basically encrypted anyways :)

I think we can use hardware encryption in this situation ?

1) Install and configure NetBackup Media Server Encryption Option (MSEO)

2) Configure NetBackup Key Management Service (KMS) ONLY if you are running LTO-4 or IBM Total Storage drives .

3) Use a 3rd party hardware device to encrypt the data.
 

We use Decru (now NetApp) devices to encrypt all of our backups, whether they're FlashBackup or not.  These appliances have now reached (or about to reach) their end of sale date.

Your other option is to investigate LTO-4 tape drives and encrypt at the drive level.  That's what we'll likely do next.

This doc is for NB 5.x, i dont find info for NB 6.x but i hope its similar only

The following limitations exist with the FlashBackup option for Windows:
 

• The NetBackup 5.0 Advanced Client license key is required on the master server
• The master server must be Windows 2000 or 2003. UNIX master server support is planned to be added later
• Clients must be Windows 2000 or 2003
• Clients must have NetBackup 5.0 installed
• Policies must be of the type FlashBackup-Windows
• Files list of the policy must be in the format: \\.\<drive_letter>:

• The ALL_LOCAL_DRIVES directive is not supported  
• User Backup and User Archive policy schedules are not supported. Only full, differential incremental, and cumulative incremental schedule types are supported
• The following policy attributes are not supported:

- "collect disaster information"

http://www.symantec.com/business/support/index?pag...

Thanks for all the responses. It's as I thought, Flashbackups don't seem to be supported for Netbackup Encryption. Will have to try encrypting them at the drive level as Ed has suggested.