A Traceable and Revocable Ciphertext Policy Attribute-Based Encryption With Policy Authentication

With the rapid advancement of cloud technology, ciphertext-policy attribute-based encryption (CP-ABE) schemes are highly suited to cloud storage environments. In order to protect sensitive information, policy-hidden CP-ABE has garnered significant attention. However, these schemes are vulnerable to fake policy attacks, where an attacker may introduce false policy and leak system information. To address this issue, we propose a traceable and revocable CP-ABE scheme with policy authentication (TR-PA-ABE). This scheme incorporates a policy checker, which is able to verify whether a ciphertext is encrypted under the correct access policy without revealing any confidential information. Additionally, it features a traceability mechanism that leverages white-box tracing to identify users who leak their keys by embedding user identities within their attribute keys. Our direct revocation method efficiently updates ciphertexts associated with revoked users without impacting the keys of other users, thus minimizing computing overhead. We formally prove that TR-PA-ABE is indistinguishable secure under chosen plaintext attacks (IND-CPA) based on the decision parallel $q$-bilinear Diffie-Hellman exponent assumption. Furthermore, our performance evaluation illustrates the practicality and efficiency of TR-PA-ABE.