Which of the following portions of the operating system typically do not make up the TCB (Trusted Computing Base)?

The Trusted Computing Base (TCB) is the foundational layer of the operating system responsible for enforcing security policies, meaning it comprises all the elements of a system that are critical to its security. These include components that directly manage access controls, enforce permissions, and prevent unauthorized actions.

User protection does not typically make up part of the TCB because it is generally a higher-level abstraction that relies on the underlying structures and mechanisms provided by the kernel and lower layers of the operating system. While user protection is crucial for security, it is often seen as a policy issue rather than a structural component of the TCB itself.

In contrast, inter-process communication, file protection, and memory protection are integral to the TCB. They involve low-level mechanisms that enforce security policies directly and manage how processes interact, how files can be accessed and modified, and how memory spaces are protected from unauthorized access. Therefore, while user protection is vital from a security standpoint, it operates on top of TCB functionalities rather than being part of it.