Enhanced secure medical data sharing with traceable and direct revocation

Sharing of the electronic medical records among different hospitals raises serious concern of the leakage of individual privacy for the adoption of the semi trustworthiness of the medical cloud platform.The tracking and revocation of malicious users have become urgent problems.To solve these problems,this paper proposed a traceable and directly revocable medical data sharing scheme.In the scheme,a unique identity parameter(ID),which was generated and embedded in the private key generation phase by the medical service provider(MSP),is used to identify legal authorized user and trace malicious user.Only when attributes satisfy the access policy and user’s ID is not in the revocation list can the user calculate the decryption key.Malicious user can be tracked and directly revoked by using the revocation list.Under the assumption of decision bilinear Diffie-Hellman(DBDH),this paper has proved that the scheme is able to achieve security against chosen-plaintext attack(CPA).The performance analysis demonstrates that the sizes of the public key and private key are shorter,and the time overhead is less than other schemes in the public-private key generation,data encryption and data decryption stages.