The Purdue model, formally the Purdue Enterprise Reference Architecture (PERA), is a structural model for industrial control systems (ICS) security that includes physical processes, sensors, supervisory controls, operations and logistics. Although the model was developed in the 1990s, it shows the different levels of critical infrastructure used in industrial facilities and how they can be protected from external and internal threats.

ALPHA uses the Purdue model as the basis of understanding with its customers.