Revocable ciphertext-policy attribute-based encryption in data outsourcing systems from lattices

Attribute-based encryption mechanism is widely used in outsourcing systems because of its characteristics of 'one-to-many' communication. However, users' attributes often change dynamically. In order to solve the problem of attribute revocation in the attribute-based encryption scheme in the outsourcing systems, a revocable ciphertext policy attribute-based encryption in data outsourcing systems from lattices is proposed. The scheme uses the LWE problem to construct the encryption and decryption algorithm, which can resist the quantum attack. Tree-access structure is adopted to realise flexible fine-grained access strategy. In addition, with the help of the data outsourcing management server, the attribute key and ciphertext are updated to achieve immediate attribute revocation. The scheme is proved to be secure under the selective attribute and selective plaintext attacks. The comparative analysis shows that the scheme has a significant improvement in performance, and it supports immediate attribute revocation, which is more suitable for the dynamic change of users in the outsourcing systems, such as social network platforms.