Research On Attribute-based Encryption Schemes In Cloud Storage

With the popularity of the Internet, cloud computing technology has been developed rapidly. Cloud storage is a derivative of cloud computing, and it won people's favorite with the advantages of low cost and easy to extend. However, the frequent security incidents make many users do not want to store their sensitive data in the cloud storage. Access control mechanism can effectively solve the problem. The attribute-based encryption is more suitable for cloud storage access control because of its ability to achieve one to many cryptograph sharing. However, the current attribute-based encryption has some problems when the access policy changes and the ciphertext local changes. Therefore, the flexible and efficient access control mechanism in cloud storage has become the focus.In this paper, we studied the access control scheme based on attribute encryption and aimed to improve the efficiency of access control. Specifically, the main work of this paper is as follows:Firstly, aimed at the problem of local change of the cipher text in cloud storage environment, a CP-ABE access control scheme based on the cipher text index is proposed. The scheme combines the ciphertext-policy attribute-based encryption, extends inverted index, imports trusted third party. Not only does it achieve the sharing of the text, but also support the local update of the text. The use of proxy re-encryption technology is ensuring the the security of the program. Theoretical analysis and experimental results show that this scheme can effectively reduce the calculation times when local ciphertext update, can quickly and effectively complete the ciphertext local update operation, and ensure the confidentiality of data.Secondly, in order to solve the problem of the policy change in the cloud storage environment, a scheme of encryption scheme based on the attribute-union of the cloud storage environment is proposed. By combining the simple attribute based encryption scheme, this scheme introduces the attribute-union, and transforms the common access structure tree to achieve the dynamic change of the access policy in the cloud storage environment. Theoretical analysis and experimental results show that the proposed scheme can effectively reduce the computing cost when the policy attributes change. At the same time, with the increase of the policy attributes, the proposed scheme can effectively reduce the overall computing cost, and effectively ensure the security of the data.In a word, we studies the problem of the dynamic change of the cipher text and the dynamic change of the access policy in the cloud storage environment. A flexible scheme of local change of the cipher text based on inverted index and a dynamic change of the encryption scheme based on the attribute-union are designed. They can effectively improve the local update rate of the cipher text and reduce the computing cost, and has a good reference and application value for the research in the cloud storage.