A Traceable and Revocable Attribute-based Encryption Scheme Based on Policy Hiding in Smart Healthcare Scenarios.

The smart medical industry, which relies on advanced Internet of Things technology and cloud platform, has been developing rapidly. Smart healthcare is a way to realize information-based communication between patients and medical staff by creating an online medical information platform. To address the user privacy and data security issues involved, we use attribute-based encryption scheme (CP-ABE). However, the traditional CP-ABE scheme has the following problems: 1. user-sensitive information is embedded directly into the access structures without hidden operations; 2. the number of public parameters is not fixed and varies linearly with the size of the system's attribute set; 3. it does not effectively fix the user attribute change problem; 4. it is impossible to trace the user. To solve the above issues, this paper proposes a scheme with the following special features: 1. using partial policy hiding; 2. using large attribute universe; 3. performing attribute revocation when user attributes are changed; 4. being able to trace back to the user after the user decryption key is leaked. Finally, we provide design details and do performance evaluation to prove its effectiveness.