On 25-05-17 11:00:26, Lee Yarwood wrote: > Hello all, > > I'm currently working on enabling QEMU's native LUKS support within Nova > [1]. While testing this work with Barbican I noticed that Cinder is > creating symmetric keys for use with encrypted volumes : > > https://github.com/openstack/cinder/blob/63433278a485b65ae6ed1998e7bc83933ceee167/cinder/volume/flows/api/create_volume.py#L385 > https://github.com/openstack/castellan/blob/64207e303529b7fceb3b8b0f0a65f8f49b3f9b26/castellan/key_manager/barbican_key_manager.py#L206 > > However the only supported disk encryption formats on the front-end at > present are plain (dm-crypt) and LUKS, neither of which use the supplied > key to directly encrypt or decrypt data. Plain derives a fixed length > master key from the provided key / passphrase and LUKS uses PBKDF2 to > derive a key from the key / passphrase that unlocks a separate master > key. > > https://gitlab.com/cryptsetup/cryptsetup/wikis/FrequentlyAskedQuestions > - 2.4 What is the difference between "plain" and LUKS format? > > I also can't find any evidence of these keys being used directly on the > backend for any direct encryption of volumes within c-vol. Happy to be > corrected here if there are out-of-tree drivers etc that do this. > > IMHO for now we are better off storing a secret passphrase in Barbican > for use with these encrypted volumes, would there be any objections to > this? Are there actual plans to use a symmetric key stored in Barbican > to directly encrypt and decrypt volumes? I've documented this as a cinder bug below, still happy to discuss this here on the ML if anyone from Cinder or Barbican disagrees with my suggestion of passphrases over symmetric keys : Cinder creating and associating symmetric keys with encrypted volumes when used with Barbican https://bugs.launchpad.net/cinder/+bug/1693840 Thanks again, Lee > [1] https://specs.openstack.org/openstack/nova-specs/specs/pike/approved/libvirt-qemu-native-luks.html > [2] http://lists.openstack.org/pipermail/openstack-dev/2016-November/106956.html -- Lee Yarwood A5D1 9385 88CB 7E5F BE64 6618 BCA6 6E33 F672 2D76