sikkerhedsmodel

A sikkerhedsmodel, or security model, is a formal framework used in information security to describe how a system protects its information and resources. It defines the goals, rules, and mechanisms that govern access control, information flow, and enforcement of security policies. Security models identify the key elements of a system, including subjects (users or processes), objects (data or resources), permissions, and the operations that may be performed, as well as the conditions under which actions are permitted.

Security models typically address confidentiality, integrity, and availability, and may specify how data moves between classifications, domains, or trust levels. They provide the formal basis for evaluating whether a policy can be consistently and correctly implemented by a given set of access-control mechanisms. Common approaches include lattice-based and rule-based frameworks, mandatory access control (MAC), discretionary access control (DAC), and role-based access control (RBAC), each with its own assumptions and enforcement strategies. Classic models used to reason about security properties include Bell-LaPadula (confidentiality), Biba (integrity), Clark-Wilson (integrity in commercial settings), and the Brewer-Nash or Chinese Wall model (conflict-of-interest prevention).

In practice, a security model guides system design and implementation in operating systems, databases, networks, and cloud environments. It supports policy formalization, access control decisions, and information-flow enforcement, while requiring careful alignment with organizational risk management, legal or regulatory requirements, and technical feasibility. Limitations include the fact that no single model captures all security facets; models must be adapted to context and kept up to date as threats and technologies evolve.