Patent attributes
In a software-as-a-service system, a federated relationship is established between a first tenant subsystem (host) and a user account on a second tenant subsystem (guest), the federated relationship including visibility controls in the host specifying resources made accessible to an authorized user of the user account. When a guest user accesses the host, an authentication is performed that includes requesting and receiving from the guest a security assertion that the user has been authenticated by the guest as the authorized user. Each tenant subsystem includes mechanisms for authenticating its own users for access control; the cross-tenancy authentication extends this operation to make and accept authentication assertions from other tenants. A second risk-based authentication may be performed for additional confidence, typically based on comparing circumstances for the present access to circumstances for past accesses.