Efficient and privacy-preserving traceable attribute-based encryption in blockchain

Attribute-based encryption, especially ciphertext-policy attribute-based encryption, plays an important role in the data sharing. In the process of data sharing, the secret key does not contain the specific information of users, who may share his secret key with other users for benefits without being discovered. In addition, the attribute authority can generate the secret key from any attribute set. If the secret key is abused, it is difficult to judge whether the abused private key comes from users or the attribute authority. Besides, the access control structure usually leaks sensitive information in a distributed network, and the efficiency of attribute-based encryption is a bottleneck of its applications. Fortunately, blockchain technology can guarantee the integrity and non-repudiation of data. In view of the above issues, an efficient and privacy-preserving traceable attribute-based encryption scheme is proposed. In the proposed scheme, blockchain technologies are used to guarantee both integrity and non-repudiation of data, and the ciphertext can be quickly generated by using the pre-encryption technology. Moreover, attributes are hidden in anonymous access control structures by using the attribute bloom filter. When a secret key is abused, the source of the abused secret key can be audited. Security and performance analysis show that the proposed scheme is secure and efficient.