Development and Evaluation of a System for Checking for Improper Sending of Personal Information in Encrypted E-Mail

There have been cases, in recent years, where customer information or other personal information has been leaked, and protective measures for personal information have become important. Corporations and other organizations have increasingly adopted software with e-mail monitoring capability to prevent leakage of personal information to the outside through e-mail. However, if the e-mail is encrypted, it is completely impossible to check whether personal information is being improperly sent. The authors have designed and implemented a system for solving such problems. Experiments to detect personal information were conducted using the implemented system, and we were able to confirm the basic effectiveness of the system. This paper reports on those results.