This thesis studies the application of fractal geometry to the application of
covert communications systems. This involves the process of hiding information
in background noise; the information being encrypted or otherwise.
Models and methods are considered with regard to two communications systems: (i) wireless communications; (ii) internet communications.
In practice, of course, communication through the Internet cannot be disassociated
from wireless communications as Internet traffic is 'piped' through a
network that can include wireless communications (e.g. satellite telecommunications).
However, in terms of developing models and methods for covert communications
in general, points (i) and (ii) above require different approaches
and access to different technologies. With regard to (i) above, we develop
two methods based on fractal modulation and multi-fractal modulation. With
regard to (ii), we implement a practical method and associated software for
covert transmission of file attachments based on an analysis of Internet traffic
noise. In both cases, however, two fractal models are considered; the first is
the standard Random Scaling Fractal model and the second is a generalisation
of this model that incorporates a greater range of spectral properties than the
first—a Generalised Random Scaling Fractal Model. [Continues.
