CMMC readiness · NIST 800-171 alignment · DFARS support Mon–Fri · 0800–1800 ET
Controls / System and Communications Protection / 3.13.8
3.13.8
SC.L2-3.13.8 · Level 2

Implement cryptographic mechanisms to prevent unauthorized disclosure of CUI during transmission…

NIST SP 800-171 Rev 2 · §3.13.8

Implement cryptographic mechanisms to prevent unauthorized disclosure of CUI during transmission unless otherwise protected by alternative physical safeguards.

Assessment objectives

From NIST SP 800-171A · 3 objectives must be met to satisfy this control
3.13.8[a] cryptographic mechanisms intended to prevent unauthorized disclosure of CUI are identified.
Examine
[SELECT FROM: System and communications protection policy; procedures addressing transmission confidentiality and integrity; security plan; system design documentation; system configuration settings and associated documentation; system audit logs and records; other relevant documents or records].
Interview
[SELECT FROM: System or network administrators; personnel with information security responsibilities; system developer].
Test
[SELECT FROM: Cryptographic mechanisms or mechanisms supporting or implementing transmission confidentiality; organizational processes for defining and implementing alternative physical safeguards].
3.13.8[b] alternative physical safeguards intended to prevent unauthorized disclosure of CUI are identified.
Examine
[SELECT FROM: System and communications protection policy; procedures addressing transmission confidentiality and integrity; security plan; system design documentation; system configuration settings and associated documentation; system audit logs and records; other relevant documents or records].
Interview
[SELECT FROM: System or network administrators; personnel with information security responsibilities; system developer].
Test
[SELECT FROM: Cryptographic mechanisms or mechanisms supporting or implementing transmission confidentiality; organizational processes for defining and implementing alternative physical safeguards].
3.13.8[c] either cryptographic mechanisms or alternative physical safeguards are implemented to prevent unauthorized disclosure of CUI during transmission.
Examine
[SELECT FROM: System and communications protection policy; procedures addressing transmission confidentiality and integrity; security plan; system design documentation; system configuration settings and associated documentation; system audit logs and records; other relevant documents or records].
Interview
[SELECT FROM: System or network administrators; personnel with information security responsibilities; system developer].
Test
[SELECT FROM: Cryptographic mechanisms or mechanisms supporting or implementing transmission confidentiality; organizational processes for defining and implementing alternative physical safeguards].

What we look for in practice

The following are placeholder notes that should be refined based on practice experience.

What assessors look for in practice. Documented evidence that this control is implemented across all CUI-handling systems within scope. Specific artifacts vary, but expect requests for written procedures, system configurations, and operational records demonstrating the control is active.

Common failure patterns. Typical issues include incomplete documentation, inconsistent implementation across systems, and missing periodic review records. Refine this section as your practice accumulates direct assessment experience.

Strong evidence looks like. Formal policy referencing this control, technical configurations demonstrating enforcement, periodic review logs with sign-off, and procedures for handling exceptions.

Scoring and POA&M context. 3-point control under the DoD Assessment Methodology. Meaningful but more contained scoring impact. Not POA&M-eligible — must be implemented at assessment time.