The hardware root of trust can be defined by four basic building blocks. Which of these is NOT one of them?

The protective hardware provides a trusted execution environment $($TEE$)$ for the privilege software to run.

The system must have the ability to generate, store, and limit the use of cryptographic keys.

At a minimum, the system must perform one or more proven cryptographic functions, like AES$-$based cryptography

A form of tamper protection must be present and available for the entire runtime.