Keystone is the identity manager service of the OpenStack cloud. An identity manager establishes user credentials and login authorization. It is essentially the starting point or entry point into the cloud. This resource will maintain a central directory of users and their access rights. This is the top level of security to ensure user environments are mutually exclusive and secure. Keystone can interface with services like LDAP in an enterprise-level directory. Keystone also maintains a token database and delivers temporary tokens to users similarly to how Amazon Web Services (AWS) establishes credentials. A service registry is used to query what products or services are available to the user programmatically.