High Dependability Computing Program Modeling Dependability(13)

Individuals and organizations increasingly use sophisticated software systems from which they demand great reliance. “Reliance ” is contextually subjective and depends on the particular stakeholder’s needs; therefore, in different circumstances, the sta

FD: Safety: index of the hazards (ISSUE) created by the system or a service FA: The adjustments and extensions concern the Software component of the Framework:

Hazards are defined as system states that can lead to human life and health

losses.

Adverse conditions are defined as all natural causes.

Attacks are defined as adversarial causes.

From the previous analysis, it results that the UMD Hardware component is stable across the various dependability attributes definitions, whereas in all cases the adjustments and extensions concerned the Software component. In particular, such adjustments concern the definitions of some of the UMD items, such as the definitions of some types of failures, or the structure of some characterization. For example, by introducing the “operational profile description” as a further element of the scope’s characterization. Such extension allows for the accommodation of different definitions of dependability attributes where the use conditions or the operation profile for the system or a service are taken into account.

At this point, to complete our evaluation of the UMD robustness, we can take into account other attributes of dependability. As above, in the following, for each definition found in literature (Literature Definition – LD), we will provide the corresponding one expressed by using the framework (Framework Definition – FD), together with the necessary framework adjustments and extensions (FA).

o LD: Confidentiality is the absence of unauthorized disclosure of information [Laprie01]. (SCOPE), which are due or not due to external events (EVENT).

FA: The adjustments and extensions concern the Software component of the Framework:

Confidentiality failures are introduced and defined as unauthorized

disclosure of information.

o LD: Integrity is the absence of improper system state alteration [Laprie01]. (SCOPE), which are due or not due to external events (EVENT).

FA: The adjustments and extensions concern the Software component of the Framework:

Integrity failures are introduced and defined as improper system state

alteration.

o LD: Robustness is the degree to which a system or component can function correctly in the presence of invalid inputs or stressful environment conditions [Bruegge04].