I have a mix of LTO 4 and LTO 3 tapes I would like to encrypt data on to. LTO 4 has built in encryption - load they key into the drive, and it handles the AES-256-GCM encyption transparently. LTO 3 has no such facility. Ideally I'd like to use some encryption software that I can pipe the
tar archive through while not having to expand my current key managment scheme beyond tracking only 256 bit keys.
Assuming OpenSSL is the ideal way to do this, I'm hoping for advice on what the best way to do it would be. It can be assumed that a key will only be used once, when a tape is overwritten a new key is made and the old one destroyed.
I'm a little worried about using a salt since data loss on the tape could destroy it, rendering all the data lost as opposed to losing 1 file if the corruption is somewhere else.
With LTO 4 the 256 bit key is loaded directly as the key. In OpenSSL if I manually specify the key I have to worry about the IV too. Should the IV be derived from they (ie a hash), or should I use the key as the password and let OpenSSL derive a its own key/IV?