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Security requirements for cooperative work: a model and its system implications

Applications involving cooperation between several users are often expressed in terms of operations on shared objects. The challenge is to provide adequate access to shared objects for cooperating principals while maintaining the required level of integrity and privacy for objects. We assume an open system environment populated with distributed and potentially shareable and persistent objects. Security mechanisms should be independent of application programs, ensuring the security of data objects regardless of the programs that are used to access them. In general, we need the ability to control access at the level of each of the operations of an object.We present a security model that reflects the structure of cooperative work, enabling users' security policies and other task requirements to be translated directly into access rights for those shared objects whose protection must be guaranteed for the successful outcome of cooperative tasks. Our model is derived from a study of some cooperative tasks in the real world [5]. The model is based on notions of group tasks, organisational roles and delegation. We consider briefly the implications of our security model for operating system design in the context of a shared object system based on a distributed shared memory model [1].