Cryptographic Protection for Message Externals
LOW MODERATE HIGHRequirements NIST SOURCE
Implement cryptographic mechanisms to protect message externals unless otherwise protected by [alternative physical controls].
Discussion (NIST Supplemental Guidance)
Cryptographic protection for message externals addresses protection from the unauthorized disclosure of information. Message externals include message headers and routing information. Cryptographic protection prevents the exploitation of message externals and applies to internal and external networks or links that may be visible to individuals who are not authorized users. Header and routing information is sometimes transmitted in clear text (i.e., unencrypted) because the information is not identified by organizations as having significant value or because encrypting the information can result in lower network performance or higher costs. Alternative physical controls include protected distribution systems.
Implementation Guidance
Original engineering commentary written for this explorer — not NIST source text and not authoritative guidance.
No engineering interpretation has been authored for SC-8(3) yet. This section is architected to receive it — see the Requirements and Assessment sections above for the authoritative NIST source content in the meantime.
Assessment
Assessment Objectives
- alternative physical controls to protect message externals are defined;
- cryptographic mechanisms are implemented to protect message externals unless otherwise protected by <SC-08(03)_ODP alternative physical controls>.
Examine
[SELECT FROM: System and communications protection policy; procedures addressing transmission confidentiality and integrity; system design documentation; system configuration settings and associated documentation; system audit records; system security plan; other relevant documents or records].
Interview
[SELECT FROM: System/network administrators; organizational personnel with information security responsibilities; system developer].
Test
[SELECT FROM: Cryptographic mechanisms supporting and/or implementing transmission confidentiality and/or integrity for message externals; mechanisms supporting and/or implementing alternative physical safeguards; organizational processes for defining and implementing alternative physical safeguards].
Overlays
STIGs & CCIs
No STIG checks or CCI mappings are currently loaded for SC-8(3). This section is architected to display, per product: STIG ID, Finding ID, Severity, Title, Description, Check, Fix, CCI, and NIST control mapping — but nothing is populated here until a real DISA STIG/CCI dataset is ingested.
Learn more about STIG/CCI integration →Evidence
Categorized from the SP 800-53A "Examine"/"Test" artifact list above by keyword — not an authoritative NIST evidence list.
Policy
- System and communications protection policy
- system security plan
Configuration
- system design documentation
- system configuration settings and associated documentation
Testing
- Cryptographic mechanisms supporting and/or implementing transmission confidentiality and/or integrity for message externals
- mechanisms supporting and/or implementing alternative physical safeguards
- organizational processes for defining and implementing alternative physical safeguards
Other Records
- procedures addressing transmission confidentiality and integrity
- system audit records
- other relevant documents or records