Data sharing is a convenient and economic service supplied by cloud computing. Data contents privacy also emerges from it since the data is outsourced to some cloud servers. To protect the valuable and sensitive information, various techniques are used to enhance access control on the shared data. In these techniques, Ciphertext-policy attribute-based encryption (CP-ABE) can make it more convenient and secure. Traditional CP-ABE focuses on data confidentiality merely, while the user's personal privacy protection is an important issue at present. CP-ABE with hidden access policy ensures data confidentiality and guarantees that user's privacy is not revealed as well. However, most of the existing schemes are inefficient in communication overhead and computation cost. Moreover, most of those works take no consideration about authority verification or the problem of privacy leakage in authority verification phase. To tackle the problems mentioned above, a privacy preserving CP-ABE scheme with efficient authority verification is introduced in this paper. Additionally, the secret keys of it achieve constant size. Meanwhile, the proposed scheme achieves the selective security under the decisional n-BDHE problem and decisional linear assumption. The computational results confirm the merits of the presented scheme.

中文翻译：

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改善云计算中基于安全性和隐私属性的数据共享

数据共享是云计算提供的一种方便且经济的服务。由于将数据外包给某些云服务器，因此数据内容的隐私性也随之而来。为了保护有价值的敏感信息，使用了各种技术来增强对共享数据的访问控制。在这些技术中，基于密文策略的基于属性的加密（CP-ABE）可以使其更加方便和安全。传统的CP-ABE仅关注数据机密性，而用户的个人隐私保护目前是一个重要问题。具有隐藏访问策略的CP-ABE可确保数据机密性，并确保不会泄露用户的隐私。但是，大多数现有方案在通信开销和计算成本上效率低下。此外，这些工作大多数都没有考虑授权验证或授权验证阶段的隐私泄露问题。针对上述问题，本文介绍了一种具有有效权限验证的隐私保护CP-ABE方案。另外，它的秘密密钥达到恒定大小。同时，该方案在决策n-BDHE问题和决策线性假设下实现了选择性安全。计算结果证实了所提出方案的优点。该方案在决策n-BDHE问题和线性决策假设下实现了选择性安全。计算结果证实了所提出方案的优点。该方案在决策n-BDHE问题和决策线性假设下实现了选择性安全。计算结果证实了所提出方案的优点。