Abstract. This paper proposes an extended framework for service provision for ubiquitous spaces based on Kerberos. The framework allows groups of services and information about ordinary users that are managed on an organizational or personal level to be combined, handling service systems with different management bases as units of Space, while defining the security relations between different spaces. A combination of spaces merges two spaces on equal terms allowing the spaces to use each others services, while a fusion of spaces represents a power-relationship where one space are allowed to use resources in another space.