Reduces message length of encrypted message to be transmitted selectively to plurality of decrypting devices. The layout schemes can be used repeatedly for multiple-stage switching network andor hierarchically arranged switching networks. , an alloy of silver as aforesaid, is a water-based composition comprising a treatment agent selected from an alkanethiol, alkyl thioglycollate, dialkyl sulfide or dialkyl disulfide and at least one of an amphoteric, nonionic or cationic surfactant in a concentration that is effective to solubilise the treatment agent.