CUI Encryption

Validated means a certificate for the module, not an approved algorithm.

AES is a FIPS-approved algorithm. Running it inside a module nobody validated does not satisfy [a]. Validation is a property of the cryptographic module, the software or hardware implementing the algorithm. The module is tested under FIPS 140 and listed with a certificate number by NIST's Cryptographic Module Validation Program (CMVP). For every product protecting the confidentiality of CUI (Controlled Unclassified Information), your evidence is that certificate number. A data sheet that says FIPS compliant is a marketing phrase, not a certificate.

The word when scopes the requirement. Find your encryption points first.

FIPS-validated cryptography is required where cryptography is the thing protecting CUI confidentiality: transmission beyond your protected environment, storage on devices that leave it, wireless and remote access. Inside the protected environment, physical safeguards can carry confidentiality, and encryption used for other purposes there does not need validation. Map the CUI flow, mark where encryption is the protection, and spend your validation effort exactly there.

On Windows, FIPS mode puts the operating system's validated modules to work.

Enable the FIPS policy setting through Group Policy or Intune so TLS and BitLocker use the validated modules, then record the module certificates for your Windows versions. Applications that call the operating system's cryptographic modules inherit that validation. Applications that ship their own cryptography do not, so check each product touching CUI for which case it is.

Encryption without validation is the one large gap the rules let you carry.

A Plan of Action and Milestones is the documented list of gaps you commit to close after assessment. 32 CFR 170.21(a)(2)(ii) permits SC.L2-3.13.11 on that plan only when encryption is employed but is not FIPS-validated. 32 CFR 170.24 scores that state as a three-point deduction, while every other requirement on a plan must be worth one point. Encryption not employed at all is a five-point deduction and cannot ride a plan. Encrypt now with what you have, then close the validation gap inside the 180-day conditional window.

One validated layer per CUI path is enough.

A FIPS-mode TLS session inside a VPN whose own module is unvalidated is still protected, because one end-to-end layer is validated. Decide which layer carries the validation for each path and record it, rather than trying to validate every layer at once. AC.L2-3.1.13 applies the same logic to remote access sessions.

Do not validate what is not protecting CUI.

Switches passing already-encrypted traffic, printers inside the physical boundary, and hashing inside an application are not employing cryptography to protect CUI confidentiality, so they carry no validation requirement. Money spent putting FIPS-validated firewalls in front of traffic that is already validated end to end buys nothing.