  The universal properties of power law and small world phenomenon of networks
seem unavoidably obstacles for security of networking systems. Existing models
never give secure networks. We found that the essence of security is the
security against cascading failures of attacks and that nature solves the
security by mechanisms. We proposed a model of networks by the natural
mechanisms of homophyly, randomness and preferential attachment. It was shown
that homophyly creates a community structure, that homophyly and randomness
introduce ordering in the networks, and that homophyly creates inclusiveness
and introduces rules of infections. These principles allow us to provably
guarantee the security of the networks against any attacks. Our results show
that security can be achieved provably by structures, that there is a tradeoff
between the roles of structures and of thresholds in security engineering, and
that power law and small world property are never obstacles for security of
networks.
