Searchable and revocable multi-data owner attribute-based encryption scheme with hidden policy in cloud storage

With the development of outsourcing data services, data security has become an urgent problem that needs to be solved. Attribute-based encryption is a valid solution to data security in cloud storage. There is no existing scheme that can guarantee the privacy of access structures and achieve attribute-based encryption with keyword search and attribute revocation. In this article, we propose a new searchable and revocable multi-data owner attribute-based encryption scheme with a hidden policy in cloud storage. In the new scheme, the same access policy is used in both the keyword index and message encryption. The advantage of keyword index with access policy is that as long as a user’s attributes satisfy the access policy, the searched ciphertext can be correctly decrypted. This property improves the accuracy of the search results. The hidden policy is used in both the ciphertext and the keyword index to protect users’ privacy. The new scheme contains attribute revocation, which is suitable for the actual situation that a user’s attributes maybe changed over time. In the general bilinear group model, the security of the scheme is demonstrated, and the efficiency of the scheme is analyzed.