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Inspired by the fact that attribute-based encryption technology can effectively realize cloud data security sharing and access control, this paper proposed a block chain data sharing model based on attribute-based encryption to ensure the privacy protection and full security in the current block chain system. The model was based on the ciphertext policy attribute-based encryption ( CP-ABE) scheme proposed by Waters. First of all, in the secret key generation phase, the data user entrusted multiple nodes to jointly calculate and store part of the private key, while other data users were not allowed to obtain the complete key, thus improving the efficiency of private key generation. Secondly, in order to prevent the abuse of key and the management of parameters in the algorithm, this paper defined a key transfer transaction data structure, and realized the accountability of CP-ABE algorithm. Finally, by building a shared chain with the function of collaborative computing and storage on and off the chain, it realized the effective integration of attribute-based encryption and block chain system. Security analysis and experimental simulation results show that the proposed model has certain optimization in the computational efficiency of key generation and actual business scenarios to meet the needs of engineering applications. [ABSTRACT FROM AUTHOR]

With the advent of the digital society, data has become an important factors of productivity. In order to fully realize the values of data, access control as a technology of data security sharing is a fundamental component of data security and data governance. Therefore, this paper proposed a cipher-text access control scheme based on blockchain aiming at improving security of cipher-text and secret key in distributed architecture. Firstly, this scheme verified the authenticity and integrity of outsourced cipher-text storage by using cipher-text generation algorithm and verifiable smart contract. Secondly, it designed an attribute key based on off-chain secure multi-party computation (SMC) to ensure the security of the user's secret key and the uniqueness of the secret key, which could reduce computational complexity of the single attribute authority, and could effectively protect the user's attribute privacy and avoided the single point of failure. Finally, through defining the formatted transaction data structure, it realized the whole process accountability of access control on the blockchain. Security analysis, performance analysis and experimental simulation results show that proposed scheme meets the requirements of general blockchain in terms of security and performance, and provides a general block chain access control scheme for data sharing. [ABSTRACT FROM AUTHOR]