Three properties that define what it means for a system to be secure — and the balance every practitioner must strike between them.
Only intended persons or recipients can access the data. Unauthorized disclosure is a failure of confidentiality.
Data cannot be altered without detection. If alteration occurs, we can identify it occurred and what changed.
Systems and services are accessible when needed by authorized users. Disruption of access is a failure.
The Tension: Pushing confidentiality and integrity to extremes restricts availability. Maximizing availability can erode confidentiality and integrity. Security design requires finding the right balance for the context — and the emphasis does not need to be equal. A public university announcement needs strong integrity but minimal confidentiality.