This monograph on Security in Computing Systems: Challenges, Approaches and
Solutions aims at introducing, surveying and assessing the fundamentals of secu
rity with respect to computing. Here, “computing” refers to all activities which
individuals or groups directly or indirectly perform by means of computing sys
tems, i.e., by means of computers and networks of them built on telecommunica
tion. We all are such individuals, whether enthusiastic or just bowed to the
inevitable. So, as part of the ‘‘information society’’, we are challenged to maintain
our values, to pursue our goals and to enforce our interests, by consciously design
ing a ‘‘global information infrastructure’’ on a large scale as well as by appropri
ately configuring our personal computers on a small scale. As a result, we hope to
achieve secure computing: Roughly speaking, computer-assisted activities of indi
viduals and computer-mediated cooperation between individuals should happen as
required by each party involved, and nothing else which might be harmful to any
party should occur.
The notion of security circumscribes many aspects, ranging from human quali
ties to technical enforcement. First of all, in considering the explicit security
requirements of users, administrators and other persons concerned, we hope that
usually all persons will follow the stated rules, but we also have to face the possi
bility that some persons might deviate from the wanted behavior, whether acci
dently or maliciously. So, in order to achieve security, we have to protect our
activities and cooperations against threatening ‘‘attackers’’. Surely, however, as in
everyday life, we also have to rely on trust in some partners. Otherwise, we would
end up with staying in complete isolation and doing nothing. Second, since we
have delegated a number of actions still increasing to computers, the components
of a computing system themselves appear as subjects: we have to decide which
components are to be trusted and which ones are to be considered as potential
attackers. Additionally, while attacks are performed by technical components, usu
ally under outside control, security enforcement also has to be achieved by use of
technical components, preferably under our own control or under the control of
trustworthy persons. Finally, we are left with a central problem of computer sci
ence: how to design, implement and verify trusted components which will enforce
our security requirements technically when running in a potentially hostile envi
ronment?