Research On Decentralized Attribute Based Encryption For Privacy Protection

In traditional medical services,the health information of patients needs to be sent to medical staff online or offline,which is neither convenient nor efficient.The cloud-based personal health record(PHR)system developed in recent years centrally stores and manages personal health information,and legitimate users can access the network and share information at any time and any place.In order to protect information and personal privacy,the personal health information owner needs to encrypt the message before uploading the information to the cloud server.At the same time,for the sake of achieving access control of the message,the information owner needs to attach an access policy to the encrypted information.Decentralized multi-authority attribute-based encryption(ABE)is an efficient and flexible encryption mechanism that does not require the central authority and cooperation among the multiple authorities to jointly generate public parameters.However,recent research works show that most of the existing schemes have defects in privacy protection and security.How to construct a decentralized attribute-based encryption scheme with privacy preserving and resistance to user collusion is still a challenge problem.For these issues,the works done in this paper are as follows: 1.The vulnerability of the Y.Rahulamathavam et al.'s scheme was analyzed and an effective collusion attack on their scheme was proposed.The attack results show that the scheme cannot resist collusion attacks.Subsequently,a new privacy-preserving decentralized KP-ABE is proposed,which avoids the existing linear attacks and achieves the user collusion avoidance.Under the standard model,the security of the scheme is reduced to decisional bilinear Diffie-Hellman assumption.The simulation results show that the computational efficiency of the scheme is significantly improved compared with the existing scheme.2.A privacy-preserving decentralized CP-ABE scheme for secure sharing of PHR is proposed,where the anonymous secret key issuing protocol is used to hide the user's identity information without knowing the user identity to generate the correct decryption key for the user.In addition,the scheme employs a one-way anonymous key agreement to hide the attributes in access policy.Based on Lewko and Waters' s scheme,the presented scheme keeps the security of the original one and removes the random oracle.Finally,the security of the scheme is reduced to simple static assumptions.