Proposing hierarchy-similarity based access control framework: A multilevel Electronic Health Record data sharing approach for interoperable environment

Interoperability in healthcare environment deals with sharing of patient's Electronic Health Records (EHR) with fellow professionals in inter as well as intra departments or organizations. Healthcare environment experiences frequent shifting of doctors, paramedical staff in inter as well as intra departments or hospitals. The system exhibits dynamic attributes of users and resources managed through access control policies defined for that environment. Rules obtained on merging of such policies often generate policy-conflicts thereby resulting in undue data leakages to unintended users. This paper proposes an access control framework that applies a Hierarchy Similarity Analyzer (HSA) on the policies need to be merged. It calculates a Security_Level (SL) and assigns it to the users sharing data. The SL determines the authorized amount of data that can be shared on successful collaboration of two policies. The proposed framework allows integration of independent policies and identifies the possible policy-conflicts arising due to attribute disparities in defined rules. The framework is implemented on XACML policies and compared with other access models designed using centralized and decentralized approaches. Conditional constraints and properties are defined that generate policy-conflicts as prevalent in the policies.