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Chapter 2. Choosing a backend

Secrets (such as certificates, API keys, and passwords) can either be stored as an encrypted blob in the barbican database, or directly in a secure storage system.

To store the secrets as an encrypted blob in the barbican database, the following options are available.

  • Simple crypto plugin - The simple crypto plugin is enabled by default and uses a single symmetric key to encrypt the blob of secrets. This key is stored in plain text in the barbican.conf file.

The simple crypto plugin is currently the only plugin supported by Red Hat.

  • PKCS#11 crypto plugin - The PKCS#11 crypto plugin encrypts secrets with project-specific key encryption keys (KEK), which are stored in the barbican database. These project-specific KEKs are encrypted by a master KEK, which is stored in a hardware security module (HSM). All encryption and decryption operations take place in the HSM, rather than in-process memory. The PKCS#11 plugin communicates with the HSM through the PKCS#11 protocol. Because the encryption is done in secure hardware, and a different KEK is used per project, this option is more secure than the simple crypto plugin.

Regarding high availability (HA) options: The barbican service runs within Apache and is configured by director to use HAProxy for high availability. HA options for the back end layer will depend on the back end being used. For example, for simple crypto, all the barbican instances have the same encryption key in the config file, resulting in a simple HA configuration.

2.1. Migrating between backends

Barbican allows you to define a different backend for a project. If no mapping exists for a project, then secrets are stored in the global default backend. This means that multiple backends can be configured, but there must be at least one global backend defined. The heat templates supplied for the different backends contain the parameters that set each backend as the default.

If you do store secrets in a certain backend and then decide to migrate to a new backend, you can keep the old backend available while enabling the new backend as the global default (or as a project-specific backend). As a result, the old secrets remain available through the old backend.