KeyCredential management functions allow the management and distribution of KeyCredentials which OPC UA Applications use to access Authorization Services and/or Brokers. An application that provides the KeyCredential management functions is called a KeyCredentialService and is typically combined with the GDS into a single application.
There are two primary models for KeyCredential management: pull and push management. In pull management, the application acts as a Client and uses the Methods on the KeyCredentialService to request and update KeyCredentials. The application is responsible for ensuring the KeyCredentials are kept up to date. In push management the application acts as a Server and exposes Methods which the KeyCredentialService can call to update the KeyCredentials as required.
A KeyCredentialService can directly manage the KeyCredentials it supplies or it may act as an intermediary between a Client and a system that does not support OPC UA such as Azure AD or LDAP.
Note that KeyCredentials are secrets that are directly passed to Authorization Services and/or Brokers and are not Certificates with private keys. Certificate distribution is managed by the Certificate management model described in 7. For example, Authorization Services that support OAuth2 often require the client to provide a client_id and client_secret parameter with any request. The KeyCredentials are the values that the application shall place in these parameters.