Transmission and Storage Confidentiality is the requirement that keeps Controlled Unclassified Information (CUI) encrypted both when it moves and when it sits at rest. It is part of the System and Communications Protection (03.13) family, and it is the control most people think of when they hear "encrypt CUI." Transmission and Storage Confidentiality (03.13.08) requires implementing cryptographic mechanisms to prevent the unauthorized disclosure of CUI during transmission and while in storage. Per the NIST discussion, this applies to internal and external networks and any system components that can transmit CUI, cryptographic mechanisms for transmission include Transport Layer Security (TLS) and Internet Protocol Security (IPsec), and information in storage refers to the state of CUI when it is not in process or in transit.
A common difficulty with this requirement is encrypting data in transit but leaving CUI at rest unencrypted, or relying on physical safeguards where R3 now expects cryptography. R3 folds the old at-rest requirement into this single control and drops the R2 option to substitute alternative physical safeguards for encryption in transit. The requirement now expects cryptographic mechanisms for both states.
Where things stand for companies facing the transition from NIST 800-171 R2 to R3:
The following is reproduced verbatim from NIST 800-171 R3, requirement 03.13.08 Transmission and Storage Confidentiality. Only the formatting has been adjusted for readability. This is a single statement with no lettered parts:
The source controls are SC-08, SC-08(01), SC-28, and SC-28(01) from NIST 800-53. There are no Organization-Defined Parameters (ODPs). Per the NIST discussion, unprotected communication paths are susceptible to interception and modification, protecting CUI in storage focuses on the state of the information rather than the type of storage device, and this requirement relates to Cryptographic Protection (03.13.11). You can read the requirement directly at NIST 800-171 R3, 03.13.08 (p. 60).
None (0). Requirement 03.13.08 contains no bracketed assignment, so there is no organization-defined value to select and nothing for the DoD to specify. The requirement applies as written.
Your System Security Plan (SSP) narrative for 03.13.08 therefore records how the requirement is implemented rather than a parameter you chose.
NIST 800-171A R3 breaks 03.13.08 into two (2) determination statements, and it has no Organization-Defined Parameters (ODPs). These AOs are:
The two (2) objectives are cryptographic protection in transit (01) and cryptographic protection at rest (02). The full guidance on assessment methods and objects, is in NIST 800-171A R3, 03.13.08 (p. 78).
Examine: system and communications protection policy and procedures; procedures for transmission confidentiality; procedures for the protection of information at rest; system design documentation; system configuration settings; cryptographic mechanisms and associated configuration documentation; information in storage requiring confidentiality protection; system audit records; system security plan.
Interview: personnel with information security responsibilities; system developers; system administrators.
Test: mechanisms for supporting or implementing transmission confidentiality; cryptographic mechanisms for supporting or implementing transmission confidentiality; mechanisms for supporting or implementing confidentiality protection for information in storage; cryptographic mechanisms for implementing confidentiality protections for information in storage.
03.13.08 maps from NIST 800-171 R2 requirement 3.13.8 (implement cryptographic mechanisms to prevent unauthorized disclosure of CUI during transmission unless otherwise protected by alternative physical safeguards), and it absorbs R2 requirement 3.13.16 (protect the confidentiality of CUI at rest), which R3 withdrew and incorporated here:
Mapped against the two (2) AOs, both (2) are direct (minimal effort), with no net-new AOs and none with no mapping. The mapping is direct, but two substantive changes matter: R3 now requires cryptographic mechanisms for CUI at rest in this control rather than in a separate requirement, and it removes the R2 allowance to use alternative physical safeguards in place of encryption for transmission. Confirm CUI is encrypted in both states rather than relying on physical protection.
Source Controls in NIST 800-53 R5:
Secure Controls Framework (SCF) Crosswalk
Organizations running a single control set across multiple frameworks can satisfy 03.13.08 through the following SCF controls:
The crosswalks from NIST 800-171 R3 and NIST 800-171A R3 to the SCF are available at no cost through the SCF Set Theory Relationship Mapping (STRM): https://securecontrolsframework.com/start-here/set-theory-relationship-mapping-strm. The STRM also carries the relationship type for each mapping (Equal, Subset Of, Intersects With), which tells you whether an SCF control fully satisfies the requirement or only part of it. Mapping above taken from SCF 2026.3.
The following are issues teams may encounter rather than certainties. They are about covering both states with cryptography, each of which needs documented evidence of due diligence and due care such as policies, standards, procedures, and configuration screenshots:
Reasonable objective evidence for an assessment is often subjective. The following examples of evidence to address NIST 800-171 R3 03.13.08 are sourced from the SCF Evidence Request List (ERL), available at https://securecontrolsframework.com/free-content/scf-download. These ERL artifacts are mapped to NIST 800-171 R3 03.13.08 through SCF controls. They establish a starting point for discussions on what an organization needs to have for evidence of due diligence and due care to withstand external scrutiny by an assessor or regulator.
Alongside these, keep the System Security Plan (SSP) narrative for 03.13.08.
With both AOs mapping directly, 03.13.08 is a moderate lift where at-rest coverage is often the gap. A realistic sequence:
How many assessment objectives does NIST 800-171 R3 03.13.08 have? NIST 800-171A R3 breaks 03.13.08 into two (2) assessment objectives. An assessor works through each one separately, so each needs its own evidence.
Which NIST 800-53 R5 controls does NIST 800-171 R3 03.13.08 come from? SC-08, SC-08(01), SC-28, SC-28(01).
How many Organization-Defined Parameters (ODPs) does NIST 800-171 R3 03.13.08 have? None (0). The requirement contains no bracketed assignment, so there is no organization-defined value and nothing for the DoD to specify.
Where does NIST 800-171 R3 03.13.08 sit in the NIST 800-171 R3 Kill Chain? Phase 19, Cryptographic Key Management. The Kill Chain is a phased model for sequencing R3 implementation, and it assigns this requirement to that phase.
03.13.08 Transmission and Storage Confidentiality implements cryptographic mechanisms to prevent the unauthorized disclosure of CUI both during transmission and while in storage. It maps directly from R2 3.13.8 and absorbs R2 3.13.16, so the objectives carry forward, but R3 now expects encryption at rest here and removes the physical-safeguard alternative for transmission. The recurring problem is encrypting in transit and leaving CUI at rest exposed. Encrypt both states with validated cryptography, and cover every component that stores or transmits CUI.
Authoritative sources:
Authoritative sources:
This guide reproduces U.S. Government text from NIST 800-171 R3 and NIST 800-171A R3. It is educational, not legal or assessment advice. Last reviewed: 2026-09-22.
