Why not compress the data before encrypting it? Seems like a really easy to implement solution that would speed up backup and recovery and cost almost nothing to implement.
In the end, it’s encrypted, compressed, decrypted, and decompressed multiple times on the way from the platter (or flash) to the tape recording head. It feels kind of dumb, really, but I’ll agree that if the computer doesn’t have the private key of the drive, stealing the data on tape will be a lot harder.
Even things like Windows Bitlocker and LUKS/dmcrypt on Linux totally ignore the drives ability to do any encryption, and do all encryption using the CPU before the drive sees the data.
Bitlocker/LUKS could easily just calculate the encryption keys and send them to the drive and trust it to encrypt/decrypt data for them... but they don't.
Source? Last I heard many companies rely on the encryption supplied by tape drive systems.
The reason is that all encryption is based on the separation of place between the encrypted data and the encryption key. Whoever can access the encrypted data must not have any way to access the encryption key.
Whenever you give your encryption key to a hardware device, or worse, when the hardware device also generates itself the encryption key, it becomes impossible to ensure that the attacker will not be able to access the encryption key.
It is impossible to know how the encryption keys are stored inside a hardware device and how and when they are erased and how easy or how difficult it will be in the future for an attacker to retrieve them.
It is impossible to believe any marketing claim of the vendor of a hardware encryption device about how tamper-resistant the device is, because such claims have very frequently been proven to be lies (even when the claims come from the largest companies, e.g. Microsoft and many others like it) and it is too difficult to distinguish truth from lies in such cases.
The only reliable means of encryption are in software, under complete end user control (or equivalently, in a custom FPGA).
That's probably one of the items on the list of reasons there are so few vendors in the space, LTO drives are essentially fungible and don't do anything interesting across vendors.