Enhanced Secure Attribute-based Dynamic Data Sharing Scheme With Efficient Access Policy Hiding and Policy Updating for IoMT

The application of 5G makes the medical Internet of Things(IoMT) bring many opportunities to the medical industry. It is expected to improve the quality and efficiency of medical services and improve people's quality of life. However, a large number of data and users are generated by smart devices in IoMT. How to access and share securely the dynamic data and manage the dynamic users has been a challenging problem at present. Many various methods were introduced to solve it. However, collusion attacks, privacy leakage, and high computational costs are not solved or only partly solved. In this paper, we analyze the most recent work at first and point out their drawbacks. Additionally, the user revocation method adopted by these schemes can not prevent revoked users from colluding with unrevoked users or the cloud to obtain shared data. Subsequently, we propose an efficient policy hiding and policy updating attribute-based data sharing scheme. The proposals support user revocation, which solves the collusion between the revoked users and unrevoked users or the cloud. Under this scheme, attributes are divided into attribute names and attribute values, and sensitive information attribute values are hidden in access policies to protect user privacy. We reduce user computational overhead by using outsourced techniques and policy update methods. The scheme is proved to be fully secure which is stronger than most of the existing works. The comparison and simulation results confirm the advantages of the proposed scheme over the available in the IoMT.