2 cissp ® Official Study Guide Eighth Edition

TCSEC Classes and Required Functionality
TCSEC combines the functionality and assurance rating of the confidentiality protec-
tion offered by a system into four major categories. These categories are then subdivided 
into additional subcategories identified with numbers, such as C1 and C2. Furthermore, 

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Select Controls Based On Systems Security Requirements 
297
TCSEC’s categories are assigned through the evaluation of a target system. Applicable sys-
tems are stand-alone systems that are not networked. TCSEC defines the following major 
categories:
Category A 
Verified protection. The highest level of security.
Category B 
Mandatory protection.
Category C 
Discretionary protection.
Category D 
Minimal protection. Reserved for systems that have been evaluated but do 
not meet requirements to belong to any other category.
The list that follows includes brief discussions of categories A through C, along with 
numeric suffixes that represent any applicable subcategories (Figure 8.6).
F I g u r e 8 . 6
The levels of TCSEC
Level Label
Requirements
D
Minimal Protection
C1
Discretionary Protection
C2
Controlled Access Protection
B1
Labeled Security
B2
Structured Protection
B3
Security Domains
A1
Verified Protection
Discretionary Protection (Categories C1, C2) 
Discretionary protection systems provide 
basic access control. Systems in this category do provide some security controls but are 
lacking in more sophisticated and stringent controls that address specific needs for secure 
systems. C1 and C2 systems provide basic controls and complete documentation for system 
installation and configuration.