Providing security and interoperation of heterogeneous systems

Interoperation and information sharing among databases independently develo ped and maintained by different organizations is today a pressing need, if not a practice. Governmental, military, financial, medical, and private ins titutions are more and more required to become part of a distributed infras tructure and selectively share their data with other organizations. This sh aring process inevitably opens the local system to new vulnerabilities and enlarges the space of possible threats to the data and resources it maintai ns. As a complicating factor, in general, data sources are heterogeneous bo th in the data models they adopt and in the security models by which protec tion requirements are stated. We present a modeling and architectural solut ion to the problem of providing interoperation while preserving autonomy an d security of the local sources based on the use of wrappers and a mediator . A wrapper associated with each source provides a uniform data interface a nd a mapping between the source's security lattice and other lattices. The mediator processes global access requests by interfacing applications and d ata sources. The combination of wrappers and mediator thus provides a unifo rm data model interface and allows the mapping between restrictions stated by the different security policies. We describe the practical application o f these ideas to the problem of trusted interoperation of health care datab ases, targeted to enforcing security in distributed applications referring to independent heterogeneous sources protected by mandatory policy restrict ions. We describe the architecture and operation of the system developed, a nd describe the tasks of the different components.