Patent ID: 9037846
Filing Date: 2015-05-19
Classification: G06F,H04L

Abstract:
1. An encrypted database system constituted with a client terminal and an encrypted database server mutually connected to each other, wherein: the client terminal comprises a storage module which stores in advance an encrypting key as well as a first and a second group generators constituting a main part of the encrypting key, a column encrypting unit which encrypts data of a column indicated by a first label of a first table inputted from outside with the encrypting key and the first group generator, encrypts data of a column indicated by a second label of a second table inputted from outside with the encrypting key and the second group generator, and transmits the encrypted first and second tables to the encrypted database server, an intra-label projection request unit which generates a first intra-label key from the encrypting key and the first label, generates a second intra-label key from the encrypting key and the second label, and transmits the first and second intra-label keys to the encrypted database server, and an inter-label projection request unit which generates a first inter-label projection key from the encrypting key, the first group generator, and the first and second intra-label keys, generates a second inter-label projection key from the encrypting key, the second group generator, and the first and second intra-label keys, and transmits the first and second inter-label projection keys to the encrypted database server; and the encrypted database server comprises a data receiving unit which receives and stores the encrypted first and second tables, and receives the first and second intra-label keys as well as the first and second inter-label projection keys, an intra-label projection unit which generates a first intra-label comparison value by having the first label and the first intra-label key worked on the data of the column indicated by the first label of the encrypted first table, and generates a second intra-label comparison value by having the second label and the second intra-label key worked on the data of the column indicated by the second label of the encrypted second table, an inter-label projection unit which generates a first inter-label comparison value which generates a first inter-label comparison value by having the first inter-label projection key worked on the first intra-label comparison value, and generates a second inter-label comparison value by having the second inter-label projection key worked on the second intra-label comparison value, and an encrypted table natural joining unit which executes natural joining on the encrypted first and second tables by utilizing the first and second inter-label comparison values.