Trusted Computing Base
The system administrator must determine how much trust can be given to a particular program. This determination includes considering the value of the information resources on the system in deciding how much trust is required for a program to be installed with privilege.
The Trusted Computing Base (TCB) is the part of the system that is responsible for enforcing system-wide information security policies. By installing and using the TCB, you can define user access to the trusted communication path, which permits secure communication between users and the TCB. TCB features can only be enabled when the operating system is installed. To install TCB on an already installed machine, you will have to perform a Preservation installation. Enabling TCB permits you to access the trusted shell, trusted processes, and the Secure Attention Key (SAK).