The present invention provides a method for protecting a character entered at a graphical interface. The method comprises the steps of: generating a set of images that form a complete image of a keypad having a button-to-character assignment; displaying the graphical keypad using said image set; and, obtaining the character of a selected button using the button-to-character assignment. The inventive method can be repeated with a different button-to-character assignment in each repetition to obtain a sequence of characters. In consequence of the inventive method, the entered character is protected as monitoring software can capture merely unreadable portions of the complete keypad image. In furtherance of this purpose, the present invention also provides a method for generating a set of images from a complete image of a character belonging to a character set.