In this section, different aspects of secure network design should be covered. The basics concepts of the cryptographic checksum to ensure message integrity and secrecy should be described. The concept of a trusted network should be developed. Of course, it is complicated by two factors:

  • the number of components/media/systems involved in a network, and
  • the fact that an active subjects interfere with other active subjects on a network.

The possibility of compromise of a node or a communications link is serious because it implies a continuing need for assurance of authenticity of any trusted network base. A paper by Randell and Rushby represents an example of separation of a distributed system into trusted and untrusted components.