Multi-keyword Searchable Encryption Scheme with Policy Hiding Support for User Revocation in Cloud Environment

Abstract In the current cloud computing environment, attribute-based access control must ensure that only authorized users can access specific sensitive data. However, the access control policies of existing solutions usually exist in plaintext form, which carries the risk of information leakage. In addition, in scenarios that require dealing with complex attack environments, its security may also be insufficient. To address these issues, we propose a dual system based multi keyword searchable encryption scheme that supports policy hiding and user revocation. In order to achieve partial concealment of access policies, user attribute values are encrypted and attribute names are attached to the ciphertext uploaded to the cloud service provider. The cloud service provider can see the names but cannot access the attribute values, effectively concealing sensitive information of access policies. The user's attributes and version number are verified by a third-party audit server. Ensure its legal authorization, only audited users can obtain the necessary ciphertext for decryption, which not only enables user revocation but also effectively prevents collusion attacks between users. Security analysis shows that this scheme utilizes a dual system encryption scheme under a fully secure model and has been proven to effectively resist keyword guessing attacks and user collusion attacks based on deterministic assumptions. According to security analysis and experimental results, the proposed solution achieves flexible cloud data storage and access while also improving security, meeting the requirements of complex cloud environments.