CLOUD STORAGE CIPHERTEXT ACCESS CONTROL SYSTEM BASED ON TABLE ATTRIBUTES

摘要

The present invention pertains to the technical field of cloud storage services, and provides a cloud storage ciphertext access control system based on table attributes and an access control method thereof. According to the system and the method, during the process of encryption, a data owner classifies leaf nodes on an access structure tree according to whether the threshold of a parent node corresponding to each leaf node is 1; the data owner further classifies a set of leaf nodes of which the thresholds of the parent nodes are 1 according to different types of parent nodes; then the data owner encrypts data according to the result of the classification and uploads the data to the cloud. In this way, the length of ciphertext obtained by the data owner, the amount of encryption calculation, and the amount of decryption calculation for subsequent sharing users are only related to an attribute set in which thresholds of parent nodes are not 1. In the access structure tree, if the threshold is 1, the parent node corresponds to an OR gate; otherwise, the parent node corresponds to an AND gate. Therefore, the system overheads are only related to an attribute set in which parent nodes are AND gates. When the number of OR gates in the access structure tree increases, the computational cost and communication overheads of the system are greatly reduced.