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Security Fundamentals & Crypto · Advanced

Security Kernel

The hardware, firmware, and software within the TCB that implements the reference monitor concept.

Definition

The security kernel enforces access control decisions for all subject-object interactions. It must isolate itself from untrusted processes, mediate all access, and be verifiable. Operating system kernels with mandatory access control, such as SELinux-enabled Linux, approximate this concept.

Example

SELinux enforcing a policy that stops a compromised web server from reading /etc/shadow.

Exam tip

Reference monitor = concept; security kernel = implementation.

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