In operating system security, what are the main stipulations and requirements of C2 level security as defined in trusted system classifications?

Introduction / Context:
C2 level security is a well known classification in trusted computer system evaluation criteria that describes a certain minimum level of protection offered by an operating system. This question checks whether you know the high level features that a system must provide to meet C2 requirements, which are often discussed in the context of secure multiuser operating systems.

Given Data / Assumptions:

• C2 is a security level in classical trusted system classifications.
• We are concerned with operating system level protection mechanisms.
• The focus is on access control, authentication and auditing features.
• No numerical or code based calculation is required.

Concept / Approach:
At C2 level, the operating system must provide discretionary access control, meaning that a resource owner can grant and revoke access to other users. The system must uniquely identify and authenticate each user, usually through login credentials, so that actions can be associated with a specific account. In addition, the system must record events in audit logs, enabling later analysis and accountability for security relevant actions. Higher levels than C2 introduce mandatory access controls and formal verification, but those are not required at C2.

Step-by-Step Solution:
Step 1: Recall that C2 is often described as controlled access protection. Step 2: Identify features of controlled access protection: each user must have a unique identity and must authenticate to the system. Step 3: The system should support discretionary access control lists or similar mechanisms so owners can control access to their objects. Step 4: The system must maintain audit logs of security relevant events to support accountability and incident investigation. Step 5: Compare these features with the given options and select the one that matches discretionary access control, user identification, authentication and auditing.

Verification / Alternative check:
Security textbooks that describe trusted computer system evaluation criteria consistently summarise C2 as controlled access protection with discretionary access controls, unique user identification and auditing. More advanced levels, such as B and A classes, mention mandatory access control and formal verification. Since those do not appear in the correct summary for C2, we can be confident that the option mentioning discretionary access control, identification, authentication and auditing is accurate.

Why Other Options Are Wrong:
Option B is wrong because physical security alone is not enough to satisfy C2, and C2 explicitly concerns software controls. Option C describes a much higher level of assurance with formal verification and mandatory multilevel security, which belongs to higher classes, not C2. Option D is clearly insecure because anonymous access with no logging contradicts the requirement for individual accountability and auditing.

Common Pitfalls:
Students sometimes mix up discretionary and mandatory access control, assuming that any secure system must implement mandatory policies. Another common confusion is between audit logging and simple event counters; C2 requires meaningful logs linked to authenticated user identities. It is also easy to think that physical measures alone determine security level, but for C2 the operating system mechanisms are critical.

Final Answer:
C2 level security requires discretionary access control, individual user identification and authentication, and auditing to provide accountability.