I'm studying for the CISSP exam and trying to wrap my mind around the concept of a Trusted Computing Base. Can someone provide a practical example? The recurring definition I see is that it's a "combination of hardware, software, and controls that work together to form a trusted base to enforce your security policy".
Initially, I was thinking that this was something like an approved vendor workstation system running a base image OS that's pre-configured for the environment... but then later in the course material, the study guide author talks about security perimeters and how the TCB can communicate with other remaining elements of the computer system that exist outside of the TCB.
Wikipedia also is a bit vague on the topic with the only example being:
AIX materializes the trusted computing base as an optional component in its install-time package management system.