Complex sentence: By default, the application encrypts the message database on the user's device and uses end-to-end encryption to secure all messages that are sent to other TextSecure users.
Split into simpler sentences: By default, the application will use end-to-end encryption to secure all messages intended to other users of the application. TextSecure encrypts both the message database on the user's device and all messages that are sent to other TextSecure users.