Encrypting ZFS

Thanks to Darren J Moffat we now have an alpha support for cryptography in ZFS.
Only bfu archives are provided for now - so if you want something more polished you've got to wait more time. Now is a good time to provide feedback, comments, etc.

Phase 1 Functionality implemented

• Per pool wrapping key (DSKEK)
• per dataset keytype.
  • pwrap: Randomly generated per dataset key wrapped by DSKEK
  • pool: Use DSKEK directly. Will likely NOT be supported in final release.
• zpool keymgr load|unload|status
  • passphrase & key in file only
• Per dataset encryption
  • NOTE: use only aes-128-cbc, aes-256-cbc
  • aes-192-cbc is broken
• Encrypted snapshots
• Clones "inherit" crypto properties regardless of path hierarchy clone promotion also works
• Encryption is a create time only property
• Encrypted datasets don't mount with 'zfs mount -a' unless key is present
• pool history records key creation/clone.