Short Abstract for 'Dynamic Security in Communication Systems'
(ISBN 3-8265-6809-5)


As of now, the provision of security (confidentiality, integrity, and
authenticity) is an all-or-nothing issue. There are no mechanisms to
fine-tune the strength of offered security and have applications use
just the right amount to deter attackers.

In this thesis, dynamic aspects of security in communication systems
are explored. This covers Quality of Service (QoS) models and
requirements for security, secure multimedia protocols, and peer and
component authentication. Each of these issues is examined, and their
dynamic properties are shown. The experimental platforms Da CaPo and
WaveVideo are used to prototype some of the results. In essence, it is
shown that it is possible to provide fine-grained, scalable security to
applications and allow them to select at runtime the required amount of
processing overhead necessary to achieve sufficient security.

One important contribution is the provision of dedicated security QoS
parameters. To this end, the new parameters are quantified by
establishing a relationship to the monetary value of data. The special
case of zero-cost attacks is also presented. Confidentiality and
authenticity are modelled from the user's perspective, and translated
down to the communication infrastructure. There, QoS parameters are
used to select protocol and algorithm properties. Functionality and
performance of a prototype have been evaluated, showing that
fine-grained control over security is feasible, and the resulting
performance is sufficient for real-world applications.

Another important contribution is the extension of multi-media
protocols to provide dynamically configurable security functionality.
In contrast to solutions that operate on a multimedia data stream
as a whole, dedicated security mechanisms that are embedded in the rest
of the multimedia protocol allow more efficient processing. They
receive QoS parameters to control their operations, and then provide
adequate confidentiality and authenticity for the transferred data. By
varying the employed algorithms and the actual data coverage of the
algorithm, computing power consumption can be reduced. This property
is critical when real-time behaviour is needed in software-only
solutions. It is studied in the context of general purpose, audio, and
video data. Results derived from a prototype are presented.