Research And Implementation Of CP-ABE With Hidden Policy In Medical Cloud

With the development of informationization and networking,the requirement of information technology becomes higher and higher.Attribute-based encryption as one of the widely used public-key cryptosystems has become a new direction of research and application of encryption,which can protect the privacy of the user effectively. In recent years, with the development of cloud computing, cloud computing brings new breakthrough for businesses. As one of the pillar industries,the medical industry also takes full of it to build the health care system. Medical can improve the phenomenon of waste of resources in the traditional medical system. As electronic health records system is one of the important part of medical cloud system, More and more users trend to store their personal health records data on the system. So people pay more attention to its safety and privacy. Attribute-based encryption with hidden policy can well be applied to the electronic health records system because of its flexible access control and privacy protection. We propose an attribute-based encryption with hidden policy, and put it into practice on the electronic health records system.In summary, main contributes of this thesis are:1、Study the current ABE scheme and focus on research the leakage of policy of ABE.On the basis of Waters construction we present a ciphertext-policy attribute based encryption scheme with hidden policy.In our scheme,the access policy is hidden by using the composite order bilinear groups,and can be expressed with Linear Secret Sharing Scheme(LSSS).Our scheme is proved chosen plaintext attacks(CPA) secure under four statics assumptions over composite order bilinear groups.2、 Give the formal definition,security model of the construction.Then describe the detail of the algorithms and employ the dual system encryption mechanism,which requires three semi-function structures to prove security. At last performance analysis is presented.Compared with Waters’ scheme,ours has more advantages.3、Simulate the electronic health records system by several highly configured computers, and implement the scheme in electronic health records system.It can be proved that our scheme can protect the privacy of the electronic health records system.