Providing an electronic message includes constructing a first digital signature of the message and a personal secret known only to a sender of the message, constructing a second digital signature of the first digital signature and the message, and sending to a receiver the message, the first digital signature, and the second digital signature. The user interface includes a digital work choosing mechanism to choose a digital work for rendering. In particular, the methods are structured into low-level device component control functions, middle-level actuator control functions, and high-level micro-droplet control functions. If the current deviation exceeds the threshold value, it is determined that an abnormality occurs in the system. The method may also include demultiplexing the input code string on the basis of the position of the synchronization code detected by the detecting, to produce kinds of compressed codes.