Privacy Preserving Spatio-Temporal Attribute-Based Access Control for Collaborative E-Healthcare

Collaborative e-healthcare leverages the benefits of the cloud to facilitate seamless collaboration and information sharing among healthcare professionals. However, ensuring the security and privacy of data in cloud environments is one of the major challenges. This chapter presents a privacy-preserving spatio-temporal attribute-based access control for collaborative e-healthcare. Our proposed cryptosystem leverages ciphertext policy attribute-based encryption to protect patient data privacy. Trapdoors corresponding to dynamic time and location attributes are added to the access policy structure, enabling verification based on dynamic parameters. These trapdoors eliminate the requirement of frequent key revocations and reassignments when the context changes. Geo-hashes of the locations are used as attributes to support location constraints. Additionally, hiding the access policy structure prevents leakage of sensitive attribute information associated with the access policy. Our proposed scheme also provides security against key escrow attacks. For practical deployment of our scheme, we introduce fog servers near the data access area that generate time and location tokens. These servers also aid in the decryption process for resource-constrained users. Security and performance analysis shows the efficacy of our proposed scheme for practical applications in e-healthcare systems, enabling precise control over sensitive electronic medical health records.