This paper introduces my honour project, an encrypted diary Android application with a location determination feature named My Secret Diary. Its aim is to provide a service for mobile device users who want to record their secret texts. My Secret Diary is a standalone application which is using SQLite as a backend database and using Google Location API to implement the location determination feature. This application allows the user to set up the current location as the secure location, which means next time when the user opens My Secret Diary, the application will check if the current position is on the setting secure location. If not, the user will not be able to access the homepage and use its functionalities.