From requirements to software trustworthiness using scenarios and finite state machine

The notion of software trustworthiness evaluation in the literature is inherently subjective. It depends on how the software is used and in what context it is used. Moreover different users evaluate a software system according to different criteria, point of view and background. Therefore to assess the software trustworthiness, it is not wise to look for a general set of characteristics and parameters; instead, there is need to define a model that is tailored to the functional and quality requirements that the software has to fulfill. This paper shows a way to model software trustworthiness by using Finite State Machine (FSM) notation and scenarios. The approach introduces a novel behavioristic model for verifying software trustworthiness based on scenarios of interactions between the software and its users and environment. These interactions consist of simple scenarios of examples or counterexamples of desired behavior. The approach supports incremental changes in requirements/scenarios. An experiment of application of the model for verifying software trustworthiness based on the scenarios of interactions between the software and its users and environment is presented in a separate case study [40].