A lead-free solder paste comprises an SnZn based lead-free solder powder mixed with a flux. Not only the key for ciphering itself in the circuits but also the information as to which of the circuits has been used for ciphering becomes the key for ciphering. The output waveform is AD converted by a converter 18 which comprises two modules 19 and 20 before transferred to a processor 50. The nutritious foods of the present invention are formulated and processed such that they resolve the dilemma that consumers have always been faced with\u2014healthy eating or enjoying what they eat.