Keystone is an OpenStack component responsible for providing authentication and authorization services to the entire OpenStack architecture. It allows users to define roles and access control policies across the entire OpenStack environment.
Keystone provides authentication via service tokens (also known as Keystone tokens). Service tokens are used to authorize requests against the other OpenStack services. The 731-KEY part of Keystone involves the seven services tokens that correspond to the services available within OpenStack. These services tokens include Identity, Image, Compute, Network, Volume, Object Storage, and Telemetry. Each token is used to access a particular service. User access control is managed by assigning roles to the tokens. These roles define what content a user or group of users can access, what actions they can perform, and how they are allowed to interact with the other OpenStack services. The 731-KEY part of Keystone ensures that users are able to access the correct content and take the right actions in a secure and controlled environment.