Abstract: With the rapid development of cloud computing, knowledge graph data outsourcing has become a popular trend. Knowledge graphs in many fields such as medical and finance have privacy- sensitive characteristics. However, cloud servers are not completely credible. In order to protect the confidentiality and integrity of data on cloud servers, encryption and other methods are used to protect the security of knowledge graph data. This paper proposes an encrypted knowledge graph storage and retrieval scheme based on searchable encryption, which can effectively protect the confidentiality and integrity of data and support retrieval on encrypted data. This scheme fully considers the necessity of sequential reading of knowledge graph entities and their relationships, thereby optimizing the encrypted index design and speeding up the retrieval efficiency. The experimental results show that the average query time of the one-hop subgraph of the encrypted knowledge graph is 2.09 times that of the non- encrypted knowledge graph, which verifies that the scheme achieves a good balance between security and query efficiency.

Key words: knowledge graph, searchable encryption, property graph, one-hop subgraph query, encrypted index