Database access method and system capable of concealing the contents of query

Abstract

A data relay server connected between a client computer and a database server produces a query message obtained by encrypting a retrieval condition designated by the client computer, and transmits the query message to the database server. The database server encrypts a specific data item which is designated by the retrieval condition and read out from the database, retrieves service information matched with the retrieval condition by encrypted data matching, and replies the service information as a retrieval result to the data relay server.

1 . (canceled)  
   
   
       2 . A data relay server for accessing a database server via a communication network, using queries received from client computers, comprising: 
 means for receiving at least two queries from different client computers;    means for producing a linked query based on said at least two queries;    means for transmitting said linked query to said database server via the communication network;    means for receiving a retrieval result for said linked query from said database server via the communication network;    means for producing individual retrieval results to be notified to said different client computers, based on said received retrieval result by applying said at least two queries, respectively.    
   
   
       3 . The data relay server according to  claim 2 , wherein each query received from said different client computers designates at least one data item to be replied as a retrieval result, and 
 wherein said linked query includes, as data items to be replied as a retrieval result, the data items designated by the queries from said different client computers.    
   
   
       4 . The data relay server according to  claim 2 , wherein the linked query includes identification information of an encryption program for encrypting retrieval condition data included in each query.  
   
   
       5 . The data relay server according to  claim 2 , wherein the linked query includes an encryption program for encrypting retrieval condition data included in each query.  
   
   
       6 . The data relay server according to  claim 2 , further comprising: 
 means for searching the retrieval result for said linked query for data matched with a retrieval condition indicated by the queries issued by each of said different client computers and producing a response message to each client computer.    
   
   
       7 . A data relay server for accessing a database server via a communication network, using queries received from client computers, comprising: 
 means for receiving a query from one of said client computers;    means for dividing the query into at least two distributive queries;    means for transmitting said distributive queries to said database server via the communication network;    means for receiving retrieval results for said distributive queries from said database server via the communication network;    means for producing another retrieval result to be notified to the client computer in response to said query, based on said received retrieval results by applying said query received from the client computer.    
   
   
       8 . The data relay server according to  claim 7 , 
 wherein each of said distributive queries received from said different client computers designates at least one data item to be replied as a retrieval result, and    wherein said each distributive query includes, as data items to be replied as a retrieval result, the data items designated by the queries from said different client computers.    
   
   
       9 . The data relay server according to  claim 7 , wherein each of said distributive queries includes identification information of an encryption program for encrypting retrieval condition data included in each query.  
   
   
       10 . The data relay server according to  claim 7 , wherein each of said distributive queries includes an encryption program for encrypting retrieval condition data included in each query.  
   
   
       11 . The data relay server according to  claim 7 , further comprising: 
 means for searching the retrieval result for said distributive queries for data matched with a retrieval condition indicated by the queries issued by each of said different client computers and producing a response message to each client computer.