| Cloud storage,as one of the important services of cloud computing,solves the difficult problems of huge data storage and data sharing.It brings people a convenient life,but it also raises problems such as data security and privacy leakage.Attribute-Based Encryption(ABE)is considered as one of the most suitable encryption methods for cloud storage environment.However,the traditional ABE mainly studies the confidentiality of data,but does not consider the protection of access policy privacy.In addition,the combination of user data may also be sensitive,so it is necessary to consider the conflict of interest relationships between different data owned by users.As the main concept in access control theory,constraint can minimize the risks that access may bring.This thesis focuses on the conflict of interest data set constraint and the hiding of access policy in attribute-based encryption.The main work of the dissertation includes:1.The characteristics of ABE mechanism are analyzed.Based on the existing ABE scheme,propose a hidden attribute outsourced decryption access control scheme based on CP-ABE to implement the obfuscation of the access policy so that we can achieve confidentiality of outsourced data and user information is not disclosed.The efficiency and security analysises are provided theoretically,with the comparision to several existing schemes.2.For the conflict of interest relations between different data in cloud storage that belongs to the same user,the definition of conflict of interest data set and conflict of interest data set constraint are proposed,and conflict of interest data set access control based on CP-ABE is proposed to enforce the conflict of interest data set constraint,thus the system can avoid loss or risk caused by an individual user's access to some or all data in the conflict of interest data set.The efficiency and security analysises are provided theoretically,with the comparision to several existing schemes. |
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