a method is provided to process data so that the data can be externally stored with minimized risk of information leakage . a framework based on virtual machines is utilized as a substitute for a trusted institution . encryption of consolidated data can reduce risk of information leakage and enhance security . since the virtual execution framework can control connection and direction of communication , financial institutions are allowed to apply encryption to data on their own , which makes the data further appropriate for external storage . by allowing financial institutions to apply their own decryption , it is possible to prevent one of two financial institutions from retrieving externally stored data into the external execution framework without intervention of the other . additionally , associated acting subjects can be provided with freedom depending on the degree of information leakage risk .