A New User Revocable Ciphertext-Policy Attribute-Based Encryption with Ciphertext Update

• Main Authors: Zhe Liu, Fuqun Wang, Kefei Chen, Fei Tang
• Format: Article
• Language: English
• Published: Hindawi-Wiley 2020-01-01
• Series: Security and Communication Networks
• Online Access: http://dx.doi.org/10.1155/2020/8856592

The revocable ciphertext-policy attribute-based encryption (R-CP-ABE) is an extension of ciphertext-policy attribute-based encryption (CP-ABE), which can realize user direct revocation and maintain a short revocation list. However, the revoked users can still decrypt the previously authorized encrypted data with their old key. The R-CP-ABE scheme should provide a mechanism to protect the encrypted data confidentiality by disqualifying the revoked users from accessing the previously encrypted data. Motivated by practical needs, we propose a new user R-CP-ABE scheme that simultaneously supports user direct revocation, short revocation list, and ciphertext update by incorporating the identity-based and time-based revocable technique. The scheme provides a strongly selective security proof under the modified decisional q-parallel bilinear Diffie–Hellman Exponent problem, where “strongly” means that the adversary can query the secret key of a user whose attribute set satisfies the challenge ciphertext access structure and whose identity is in the revocation list.