Abstract: In a system for easily realizing security in a homenetwork by preventing communication from being made with a terminal illegally connected to the homenetwork, an information appliance and a key management server are connected to a homenetwork via network connector. By inserting an authentication tag into the information appliance, authentication with the key management server is performed and a public encryption key for allowing communication to be made with another information appliance connected to the homenetwork is obtained, thereby enabling safe communication to be made in the homenetwork.

Abstract: An apparatus that obtains a straight discharge arc during the whole lighting period, as well as provides a discharge lamp-lighting apparatus which can form a plurality of luminous intensity distribution patterns by changing the shape of the discharge arc. By supplying a lighting waveform equal to an acoustic resonance frequency which lighting waveform excites the mode to make the discharge arc straight. The acoustic resonance frequency is determined by the sound velocity in the discharge space medium and the height of a section orthogonal area to the electrode axis to the discharge lamp. The shape of the discharge arc at the time of rated lighting can be made substantially straight. By supplying the lighting waveform which amplifies the amplitude of the compressional wave emitted from the discharge arc during the period when the vapor pressure of the filler of the discharge lamp is low, the shape of the discharge arc can be made straight during the whole lighting period.