Research On Attribute Base Encryption Scheme Based On Ciphertext Policy

With the advent of the era of big data,cloud computing and block chain technology have attracted wide attention.Because cloud servers have abundant storage space,data owners can store their data conveniently and quickly to cloud servers.However,the stored data may contain the sensitive information of the data owner,which makes it impossible to protect the privacy and security of the data.Block chain technology uses chain data structure to validate and store data,which has characteristics by openness,transparency,and de-trust.It achieves efficient and reliable data interaction,however it only faces serious privacy leaks.Therefore,it is an urgent problem to realize effective data sharing and protect data privacy.Attribute-based encryption has flexible access control strategy,which can not only achieve efficient "one-to-many" data encryption information sharing,but also realize fine-grained access control for different users.In practical applications,data users may need to revoke attributes,retrieve data and protect privacy of data information.According to the above requirements,we study the attribute-based encryption based on ciphertext strategy.The main work includes the following three aspects:(1)Based on the requirement of data users with attribute revocation,an attribute-based encryption scheme for attribute revocation in multi-attribute authorization environment is designed,which combines attribute-based encryption with proxy re-encryption technology of ciphertext policy.The scheme uses access control tree to manage the attribute issued by different attribute authorization agencies,which can effectively resist the joint attacks of multiple attribute authorization agencies.At the same time,the version number tagging method is used to revoke the user's attributes,ensure fine-grained access,and effectively protect the privacy of data users.(2)To solve the problem of user data retrieval,cloud filtering server,cloud search server and cloud storage server cooperate to solve the problem of cloud server authorization service.At the same time,most of the existing attribute-based searchable encryption schemes are suitable for searching keyword ciphertext.Therefore,an attribute-based encryption scheme based on authorized searchable ciphertext strategy is designed.This scheme can not only provide data retrieval services for all ciphertext,but also realize fine-grained access for users on the premise of ensuring data confidentiality,solve the problem of key leakage for data users,and improve the retrieval efficiency of cloud data for data users.(3)In order to meet the need of privacy protection of transaction data in block chain,an attribute-based encryption scheme based on ciphertext strategy is designed to protect the privacy of transaction data in block chain.The scheme uses short signature technology to secure signature of transaction data,and encrypts transaction privacy information in block chain based on attribute,thus avoiding the leakage of data privacy.