Attribute Encryption And Its Application And Research In The Mobile Health Privacy Protection

As a new medical management model,mobile health has received extensive attention and use.However,existing mobile health systems usually have problems such as unclear access permissions,unable to support hierarchical identity-based user revocation and so on,which makes the privacy of the user's under a serious threat.Therefore,at the premise of giving full play to the advantages of mobile health,how to ensure the personal privacy and data security is an important research problem.As a new type of cryptosystem,attribute-based encryption has some excellent features,such as privacy protection,anonymity,flexible access structure and so on,so that it is able to realize the fine-grained access control of data effectively and has provided a new research direction to solve the problem of privacy protection in the mobile health.In this paper,we focus on the issue of user's permissions change problem in mobile health system,and then exploit cryptography techniques to construct efficient and secure identity-based revocable attribute encryption algorithm.The main contributions and innovations of this thesis include the following aspects:1.In order to solve the frequent user's permissions change problem in mobile health,we construct a large universe encryption algorithm and design an attribute-based encryption scheme which can realize hierarchical identity-based revocation.The scheme realizes user revocation from the perspective of encryption by embedding user identity and revoked user identity respectively in user's private key and ciphertext,and implements affiliation-based user revocation by introducing hierarchical identity structure.And the scheme does not need to update the user's private key when user revocation occurs.Therefore,key management overhead is much lower in the hierarchical identity-based revocable encryption algorithm for both the users and the trusted authority.At the same time,the trusted authority could be offline after system setup and key distribution.Security analysis and performance evaluation show that the scheme is safe and efficient.2.In order to solve the low efficiency of the attribute-based encryption algorithm,we introduce the idea of outsourcing compute and design a hierarchical identity-based revocable ciphertext-policy attribute-based encryption scheme with verifiable outsourcing decryption on the basis of hierarchical identity-based revocable encryption algorithm.The scheme outsources complex calculations in the decryption process of the hierarchical identity-based revocable encryption algorithm to the cloud server,which makes the hierarchical identity-based revocable encryption algorithm have less user's local computation and can realize the result verification of outsourcing compute at the same time.Security analysis and performance evaluation show that the scheme is safe and efficient.3.In order to solve the multiple identities revocation problem in mobile health system,we expand the above scheme and propose an attribute-based encryption scheme with hierarchical identity-based multiple user revocation,which solves the problem of revoking multiple users or organizations at the same time effectively.The scheme can further improve efficiency based on the idea of multithreading at the time of implementation.The scheme's efficiency,the anti-collusion attack,the privacy protection and the multiple user revocability make the scheme practical.