Traceable and revocable multi-authority attribute-based keyword search for cloud storage

Ciphertext-Policy Attribute-Based Keyword Search (CP-ABKS) provides data privacy and achieves fine-grained access control over encrypted data in the cloud. However, authorized users may misuse the secret key for financial benefits in a multi-user scenario. Thus, tracing those malicious users and revoking them from the system is essential. Alongside this, most existing schemes have only a single authority to generate the secret key, which may lead to misuse of the secret key. To address these problems, this paper proposes a traceable and revocable multi-authority attribute-based keyword search in the cloud. The scheme involves two authorities generating the user secret key to restrict any individual authority's unauthorized access to cloud data. The scheme also traces malicious users and revokes them from the system. Further, we prove that the scheme is secure against chosen keyword attacks, chosen plaintext attacks, and traceability. And also verify the security against malicious authorities. The performance analysis shows that the proposed scheme is efficient in computation cost compared to the state-of-the-art schemes.