Use Cases

Image signature verification

Verification of image signatures assures that an image is not replaced or changed since the time of original upload. The image signature verification feature uses Castellan as its key manager for storing cryptographic signatures. An image signature and certificate UUID is uploaded along with the image to the Image (glance) service. Glance verifies the signature after retrieving the certificate from the key manager. When the image is booted, the Compute service (nova) verifys the signature after it retrieves the certificate from the key manager.

For more details, see the Trusted Images documentation.

Volume encryption

The volume encryption feature provides encryption of data-at-rest using Castellan. When a user creates an encrypted volume type, and creates a volume using that type, the Block Storage (cinder) service requests the key manager to create a key to be associated with that volume. When the volume is attached to an instance, nova retrieves the key.

For more details, see the Data Encryption section. and Volume encryption.

Ephemeral disk encryption

The ephemeral disk encryption feature addresses data privacy. The ephemeral disk is a temporary work space used by the virtual host operating system. Without encryption, sensitive user information could be accessed on this disk, and vestigial information could remain after the disk is unmounted.

The ephemeral disk encryption feature, can interface with a key management service through a secure wrapper and support data isolation by providing ephemeral disk encryption keys on a per-tenant basis. Back-end key storage is recommended for enhanced security (for example, an HSM or KMIP server can be used as a barbican back-end secret store).

For more details, see the Ephemeral disk encryption documentation.


Sahara generates and stores several passwords during the course of operation. To harden sahara’s usage of passwords it can be instructed to use an external key manager for storage and retrieval of these secrets. To enable this feature, there must first be an OpenStack Key Manager service deployed within the stack.

With a Key Manager service deployed on the stack, sahara must be configured to enable the external storage of secrets. Sahara uses the Castellan library to interface with the OpenStack Key Manager service. This library provides configurable access to a key manager.

For more information, see the Sahara advanced configuration guide.


To provide access to Docker Swarm or Kubernetes using the native clients (docker or kubectl respectively) magnum uses TLS certificates. To store the certificates, it is recommended to use Barbican , or the Magnum Database (x590keypair).

A local directory can also be used (local), but is considered insecure and not suitable for a production environment.

For more details on setting up a certificate manager for Magnum, see the Container Infrastructure Management service documentation.


The LBaaS (Load-Balancer-as-a-Service) feature of Neutron and the Octavia project need certificates and their private keys to provide load balancing for TLS connections. Barbican can be used to store this sensitive information.

For more details, see How to create a TLS Loadbalancer and Deploy a TLS-terminated HTTPS load balancer.


Symmetric keys can be used to encrypt Swift containers to mitigate the risk of users data being read if an unauthorised party were to gain physical access to a disk.

For more details, see Object Encryption within the official swift documentation.

Passwords in Config Files

The configuration files for the OpenStack services contain a number of passwords which are in plain text. These include, for instance, the passwords used by service users to authenticate to keystone to validate keystone tokens.

There is no current solution to obfuscate these passwords. It is recommended that these files be appropriately secured by file permissions.

There is currently an effort underway to store these secrets in a Castellan back-end and then have oslo.config use Castellan to retrieve these secrets.