Group-Oriented Cryptosystem for Personal Health Records Exchange and Sharing

Personal health records (PHRs) have been developed into a type of patient-centered health information exchange model in recent years. PHRs are concentrated in a data center established by a service provider through the Internet. From any location, at any time, with only a web browser and an Internet connection, users can access the PHR service provider to establish, control, and manage their personal health data. This PHR standard enables powerful saving, reading, and sharing of medical information. PHR management in the cloud must consider the security of the cloud computing environment. Apart from traditional service providers encrypting healthcare records, PHR cloud providers should provide a group-oriented cryptosystem for users. Accordingly, the proposed bilinear pairing-based group-oriented cryptosystem has the following advantages: (1) The cryptosystem can simultaneously realize four decryption strategies, enabling receivers to designate appropriate decryptors according to the content of plaintext. (2) All group members need only one private key, which can be used for decryption regardless of the decryption modes. Therefore, errors resulting from the misuse of keys can be avoided, and the difficulty of key management can be reduced. (3) The system is required to disclose only six parameters, thus decreasing spatial complexity. (4) Regardless of the encryption and decryption modes, receivers must perform encryption only one time, and the length of the ciphertext comprises only four parameters. Thus, the proposed cryptosystem computing (including environment setting and the processes of encryption and decryption) is highly efficient, with easy key management, low spatial complexity, and small amount of ciphertext being transmitted.