Models ((free)) - Information Security

Consider a financial audit system. A low-integrity source (e.g., an unverified internet poll) cannot write into the high-integrity general ledger (No Write Up). Likewise, the ledger system should not read from that unverified source (No Read Down).

In 1987, David Clark and David Wilson developed the Clark-Wilson model, which integrates multiple security goals, including confidentiality, integrity, and availability. The model introduces the concept of: information security models

No single model suffices for a modern enterprise. Real-world security architectures combine them: Consider a financial audit system

A consultant working on a merger between two banks is walled off from viewing any confidential data about other banks in the same sector. This model perfectly balances productivity (initial free access) with ethical separation. In 1987, David Clark and David Wilson developed

Far from being mere academic exercises, these models underpin everything from your smartphone’s file permissions to national intelligence databases. Below, we break down the foundational models that continue to shape the cybersecurity landscape.