关键词: 可搜索加密, 属性基加密, 区块链, 云辅助, 细粒度访问控制

Abstract: Searchable encryption technology can effectively solve the problem of searching encrypted data without decryption. In view of the fact that the existing searchable encryption technology does not consider the problem of fine-grained search permission of data users, and the problem of data security and privacy protection caused by the centralization of cloud storage in the existing searchable encryption schemes, this paper proposes a cloud-assisted attribute-based searchable encryption scheme on blockchain. In this scheme, searchable encryption technology is used to realize secure search of encrypted data on the blockchain, attribute-based encryption technology is used to realize fine-grained access control of data, and the immutability of the blockchain is used to ensure the security of keyword ciphertext. In this scheme, attribute-based encryption technology is used to encrypt keywords extracted from data files. The keyword ciphertext is uploaded to the blockchain in the form of a transaction. Keyword ciphertext and encrypted data files are stored on the semi-trusted cloud server. Based on the assumption of difficult problems, it is proved that the scheme can guarantee the security of keyword ciphertext and trapdoor. And important information related to keywords and trapdoors will not be leaked.The numerical experimental results show that the proposed scheme is more efficient in the key generation phase, trapdoor generation phase, and keyword search phase than the existing similar schemes.

Key words: searchable encryption, attribute-based encryption, blockchain, cloud-assisted, fine-grained access control