关键词: 云存储, 访问控制, 密文策略的属性加密算法, 合谋攻击, 判断双向性Deffie-Hellman假设

Abstract: An access control scheme for cloud storage proposed by Tang et al. (TANG Y，LEE P，LUI J，〖WTBX〗et al.〖WTBZ〗 Secure overlay cloud storage with access control and assured deletion. IEEE Transactions on Dependable and Secure Computing，2012，9(6)：903-916） was analyzed and proved to be vulnerable to collusion attacks, and a detailed attack method was given. To address this problem of the given scheme, this paper took the advantage of the property of collusion attack resistant of the attribute based encryption algorithm and improved a ciphertext-policy attribute-based encryption (CP-ABE) algorithm which used the access tree. Then the improved algorithm could be used seamlessly into the access control and assured deletion scheme for cloud storage without changing the cloud server. Finally, the security against the chosen plaintext attack was proved under the Decision Bilinear Diffie-Hellman (DBDH) assumption, and the ability of resisting the collusion attack of the scheme was proved by analyzing a practical cloud situation.

Key words: cloud storage, access control, CP-ABE algorithm, collusion attack, Decision Bilinear Diffie-Hellman (DBDH) assumption