Method for retrieving encrypted graph, system for retrieving encrypted graph, and computer

A system for retrieving an encrypted graph, comprising:

• a first computer, which comprises a processor and a memory, and is configured to generate an encrypted graph by encrypting a graph including a start point, an edge, and an end point;
• and
• a second computer, which comprises a processor and a memory, and is configured to retrieve the encrypted graph,
• the first computer further comprising:
• a secret key generation module configured to generate a secret key through use of a secret key generating function of a searchable encryption algorithm set in advance;
• an encrypted graph data generation module configured to:
• generate the encrypted graph by encrypting the graph through use of an encryption function of the searchable encryption algorithm;
• generate an encryption query by encrypting a query for retrieving the graph through use of a searchable encryption query function of the searchable encryption algorithm;
• and
• transmit encrypted graph data obtained by associating the encrypted graph with the encryption query for each edge of the graph and a searchable encryption matching function of the searchable encryption algorithm to the second computer;
• and
• an encrypted graph retrieval query generation module configured to:
• generate an encrypted graph retrieval query by encrypting the start point and the end point of the graph to be retrieved through the use of the searchable encryption query function;
• and
• transmit the encrypted graph retrieval query to the second computer,
• the second computer further comprising an encrypted graph retrieval module configured to:
• receive and store the encrypted graph data and the searchable encryption matching function;
• receive the encrypted graph retrieval query;
• execute retrieval processing through use of the searchable encryption matching function with the encrypted graph retrieval query and the encrypted graph data being used as input;
• and
• transmit a result of the retrieval processing to the first computer.

A computer, comprising:

• a processor;
• and
• a memory comprising:
• encrypted graph data formed of a plurality of values obtained by encrypting respective values of a plurality of start points, edges, and end points included in graph data through use of a first function of a searchable encryption algorithm;
• and
• a plurality of encryption queries obtained by encrypting search queries of the respective values of the plurality of start points, edges, and end points included in the graph data through use of a second function of the searchable encryption algorithm,
• the encrypted graph data and the plurality of encryption queries being recorded in the memory in association with each other for each data set formed of a start point, an edge, and an end point.