A method is provided to process data so that the data can be externally stored with minimized risk of information leakage. A framework (virtual execution framework) based on virtual machines (VMs) 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.