Abstract: Aiming at the security and privacy of data in the process of data sharing under cloud computing, An attribute-based encryption scheme with high efficiency and flexibility under cloud computing is proposed. The scheme encrypts the cloud storage data using the ciphertext policy attribute base algorithm, and the trusted third party adds the global identity to the user attribute set and aggregates the attribute public key associated with the ciphertext policy with the fixed-length ciphertext strategy so that the The ciphertext length is constant. The scheme effectively prevents the security risks caused by the conspiracy attack on the user data, selects the appropriate encryption algorithm and efficient public key encryption processing way to ensure the privacy of the dynamic data in the data sharing process, and achieves the data security at the lower cost Shared goals.

Key words: Cloud computing, Ciphertext-policy attribute-based encryption, Fixed length ciphertext, Efficiency, Flexibility

摘要： 针对云计算下数据共享过程中数据的安全性与隐私性问题，提出云计算下高效灵活的属性基加密方案。方案针对云存储数据采用密文策略属性基算法进行加密，可信第三方在用户属性集中添加全局标识，并利用定长密文策略将与密文策略相关的属性公钥聚合起来进行加密，使得密文长度常量化。方案有效防止串谋攻击行为对用户数据带来的安全隐患，选取合适的加密算法及高效的公钥加密处理方式，以保证数据共享过程中动态数据的隐私性，实现以较低开销进行数据安全共享的目标。

关键词: 云计算, 密文策略属性基加密, 定长密文, 高效性, 灵活性