Secure and Efficient General Circuits Attribute-Based Access Control in Cloud Computing

The access structure of a general circuit can represent the access control policy flexibility and has broad applications in the field of dense data access control. All previous proposals are declared to support fined-grain access control for encrypted data and secure sharing in cloud. However, these schemes have their limitations, as the circuit nodes can only output layer by layer, and the circuit depth of the access structure implemented in the system is a fixed value. In addition, recent results show that these schemes have serious security defects, such as unresisting collusion attacks and vulnerability of the ciphertext stored in cloud. This article aims at solving the problems mentioned above and a scheme with improved efficiency and security is proposed. In the presented scheme, the circuit access structure with any depth less than or equal to the maximum depth is realized through equivalent conversion of circuit. By modifying the parameter form of shares, we solved the limitation that the previous scheme could only output layer by layer upward, and realized that each node could output to any node with a depth greater than its own across layers. This scheme greatly reduces the redundant computational overhead and improves the encryption and decryption efficiency.