Abstract
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.
Highlights
As a special kind of public key encryption (PKE), attributebased encryption (ABE) is a one-to-many cryptographic primitive that can offer a fine-grained access control
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
Our 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
Summary
As a special kind of public key encryption (PKE), attributebased encryption (ABE) is a one-to-many cryptographic primitive that can offer a fine-grained access control. Wang et al in [23] proposed a new revocable CP-ABE that incorporates ID-based revocation ability In their security definition, 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. We propose a R-CP-ABE scheme that can implement user direct revocation, maintain a short revocation list, and update ciphertext by incorporating the identity-based and time-based revocable technique. Our 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
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