Treat TLS configuration as a tested compatibility and cryptography decision

Bottom line: a TLS change can improve cryptographic posture and still break a critical client, inspection path, device, or integration. Inventory the real endpoints and intermediaries, choose configuration from current official guidance, and test negotiation and application function before broad enforcement.

Source fact: what NIST covers

NIST SP 800-52 Revision 2 provides guidance for selecting, configuring, and using TLS implementations with FIPS and NIST-recommended algorithms. Its scope includes protocol support, cipher configuration, certificates, and security-relevant TLS extensions for U.S. Government systems.

The NIST page also carried a May 7, 2026 planning note stating that the publication was under review. That is a reason to check for a later final revision before using specific protocol or algorithm requirements. It is not a reason to invent a replacement requirement.

What the source does not establish

The publication does not certify a server, client, proxy, appliance, library, or cloud service. Successful TLS negotiation does not establish application authorization, endpoint integrity, certificate lifecycle health, or correct handling of data before encryption and after decryption.

Federal requirements do not automatically become legal requirements for every private organization. Contractual, sector, customer, and platform requirements must be established separately. Product support and defaults can also change by version.

Applicability questions

Which clients, servers, libraries, proxies, load balancers, scanners, devices, and third parties terminate or inspect each TLS flow?

Which protocol versions, algorithms, extensions, certificate types, names, and trust stores do they actually support?

Where is traffic decrypted, and which identities can change or observe that point?

What fails if negotiation is rejected or certificate validation changes?

Which current authority defines the required cryptographic profile for this environment?

DSE recommendation: stage the complete connection

The following steps are DSE recommendations based on the cited source.

Build a flow inventory naming both endpoints, every intermediary, owners, application purpose, certificate authority, library or platform, supported versions, and business criticality.

Select an approved target from the latest applicable official and product guidance. Record the date, scope, and any exception rather than copying a generic internet configuration.

Test representative clients, devices, automation, APIs, failover paths, monitoring, and external integrations. Capture the negotiated protocol and algorithm plus application-level results.

Protect private keys, trust stores, termination points, and configuration changes. Review who can export keys, add trust, weaken policy, or bypass validation.

Roll out in measured stages with failure telemetry and rollback criteria. Do not leave an undocumented legacy listener after the migration.

Re-scan and functionally test after enforcement, library upgrades, certificate changes, proxy changes, or recovery activation.

Verification and evidence

Retain the connection inventory, approved profile and source date, endpoint and intermediary configurations, representative negotiation results, certificate validation tests, application tests, failure logs, exceptions, rollout record, and rollback or closure evidence. A port scan alone is not complete functional proof.

Official references

NIST SP 800-52 Rev. 2 — Guidelines for the Selection, Configuration, and Use of TLS Implementations — National Institute of Standards and Technology; finalized August 29, 2019; page noted as under review on May 7, 2026