关键词: 云存储, 访问控制, 密文策略属性基加密, (k, n)算法, 数据机密性

Abstract: Concerning the data's confidentiality when stored in public cloud storage system and the system's performance, a secure and efficient scheme was proposed and applied in the cloud storage system of cryptography with cryptographic fine-grained access control, which was based on Ciphertext-Policy Attribute-Based Encryption (CP-ABE). In the proposed scheme, the original data were firstly divided into a number of slices by the (k,n)algorithm. Then some of slices were randomly chosen to encrypt. At last, the encrypted slices were published to the cloud storage, and only one copy of these slices was stored. The proposed scheme was proved that it could improve the performance of the user's cancel operation and reduce the cost of the storage space. At the same time, the system was also proved to be safe on calculation by the analysis of the security. By contrast, the experimental results show that, the data management time for the data owner is decreased obviously through optimizing the user revocation phase. The data storage cost is also decreased because of only storing one copy of data. The proposed scheme achieves secure sharing and efficient storage of the sensitive data in the public cloud storage.

Key words: cloud storage, access control, Ciphertext-Policy Attribute-Based Encryption (CP-ABE), (k,n) algorithm, data confidentiality