Encrypting backup tapes
Encrypt at the application level (before it is sent to the backup device) and you only need to encrypt the data you care about, which can make data restoration and validation easier. And if data is encrypted in the application, rather than when it is written to the backup media, it’s less likely to be sent in the clear from the application across the network, which can introduce vulnerabilities elsewhere in the system.
On the other hand, applying granular backup policies to application data can be a complex and gruelling process, because you’re likely to have to build that directly into the server application’s database.
Encrypting at the point of backup gives you two options: an in-line encryption device from a company like CipherMax (www.ciphermaxinc.com), or a system that encrypts directly on the device. The LTO 4 standard for tape drives from the LTO Consortium now includes native AES encryption capabilities, so that the device itself handles backup.
Check how you manage the keys; most encryption software has its own key management capabilities, but with several customers to deal with you’ll want to centralise it. The forthcoming IEEE 1619.3 standard, defining how a key manager sends keys to a device like a tape drive, or an application, promises better separation between the management system and the device using the key.