Abstract: A messaging application configured to provide a messaging interface on which outgoing messages from a user, to contacts can be composed and incoming messages from the contacts can be viewed. Moreover, the messaging application is configured to store message data in an encrypted form as a database file. Furthermore, the messaging application is configured to require the user to input a predetermined access code before giving access to the messaging interface. Moreover, the messaging application is configured to provide a first mode in which the user is given access to all message data when a first predetermined access code is input, and a second, secret mode in which the user is given access to only a subset of all the message data, when a second predetermined access code is input by the user.

Abstract: A user device stores a messaging application and an encrypted database, processor and has a key store storing an authorisation token to be used by the messaging application. The messaging application is configured, in the unlaunched state, to retrieve the authorisation token from the key store to perform communication with the messaging server on receipt of an incoming call from the messaging server and to display a notification without contact information, and is configured, in the launched state, on receipt of an incoming call from the messaging server to retrieve the authorisation token from volatile memory to perform communication with the messaging server, and to display a notification of the incoming call with contact information for a calling party, on the display of the user device. The encryption key for the database is generated based on a user passcode, and the user device stores neither the user's passcode nor a hash of the passcode.