  In this paper, we survey the state of the art of the secure key exchange
method that is secured by the laws of classical statistical physics, and
involves the Kirchhoff's law and the generalized Johnson noise equation, too.
We discuss the major characteristics and advantages of these schemes especially
in comparison with quantum encryption, and analyze some of the technical
challenges of its implementation, too. Finally, we outline some ideas about how
to use already existing and currently used wire lines, such as power lines,
phone lines, internet lines to implement unconditionally secure information
networks.
