Method for user authentication in a device comprising a touch screen

A method for user authentication in a device comprising a touch screen is provided. In operation, the device stores a user authentication code corresponding to a user. When a trigger for user authentication is detected, the device randomly selects one or more character positions in the sequence of characters. The device further requests the user to enter a character corresponding to each of the selected one or more character positions in the sequence of characters. When the device detects a user entry made using a keypad on the touch screen, the device determines whether the user entry matches a character corresponding to each of the selected one or more character positions. When the user entry matches a character corresponding to each of the selected one or more character positions in the sequence of characters, then the user is successfully authenticated to the device.