Keystone provides a single point of integration for OpenStack policy, catalog, token and authentication.
keystonehandles API requests as well as providing configurable catalog, policy, token and identity services.Each Keystone function has a pluggable backend which allows different ways to use the particular service. Most support standard backends like LDAP or SQL, as well as Key Value Stores (KVS).
Most people will use this as a point of customization for their current authentication services.
