Agencies should move certificate issuance, renewal, and revocation into a governed lifecycle model that can run in parallel with legacy systems during migration. The goal is to cut manual handling and improve visibility without breaking trust chains. That means inventorying all authorities, setting policy-based workflows, and phasing migration by certificate risk rather than by convenience.
Why This Matters for Security Teams
Legacy PKI is often treated as an infrastructure housekeeping problem, but for agencies it is an operational risk surface that affects availability, trust, and auditability at the same time. Manual certificate handling creates brittle dependencies on a few administrators, while expired, misissued, or orphaned certificates can break authentication in ways that are difficult to detect early. Current guidance aligns with lifecycle governance in the NIST Cybersecurity Framework 2.0 and with broader non-human identity control practices described in Ultimate Guide to NHIs.
The real issue is not whether certificates exist, but whether issuance, renewal, and revocation can be governed at machine speed without forcing outages during migration. Agencies that delay modernisation often inherit hidden certificate sprawl across VPNs, apps, devices, and internal services, which makes even basic renewal a change-management event. NHI Mgmt Group reports that only 5.7% of organisations have full visibility into their service accounts, a useful proxy for how little operational insight many teams have into machine identities overall. In practice, many security teams encounter certificate failures only after authentication has already broken in production, rather than through intentional lifecycle control.
How It Works in Practice
The safest way to reduce PKI burden is to separate the control plane from the authentication plane. Agencies can keep existing trust chains active while moving certificate operations into a governed lifecycle model that enforces policy, logs every action, and removes manual ticket handling wherever possible. That typically means centralising inventory first, then automating issuance and renewal with policy-based workflows, and finally tightening revocation and replacement processes as migration progresses.
Operationally, the model works best when certificates are treated as managed non-human identities rather than one-off artefacts. Teams should identify certificate owners, service dependencies, expiration windows, key lengths, and trust anchors before changing anything. From there, renewal can be orchestrated through short-lived issuance, approval rules for higher-risk systems, and automated revocation when a workload is retired or replaced. This is where standards-oriented thinking matters: NIST Cybersecurity Framework 2.0 supports asset visibility and protective process maturity, while Ultimate Guide to NHIs frames lifecycle governance as a core defence against credential drift and orphaned access.
- Inventory every issuing authority, intermediate CA, certificate consumer, and renewal dependency.
- Classify certificates by business criticality so high-risk services migrate first, not merely the easiest ones.
- Automate renewals with policy checks, approval gates, and alerts for exceptions that still need human review.
- Keep legacy PKI running in parallel until replacement paths have been tested and rollback is documented.
- Revoke and retire certificates as part of application decommissioning, not as an afterthought.
This approach reduces manual load without disrupting authentication because the old and new paths coexist until trust is proven at each stage. These controls tend to break down when agencies lack an authoritative asset inventory and cannot map certificates to dependent systems, because unknown consumers will fail when a chain or renewal path changes.
Common Variations and Edge Cases
Tighter certificate governance often increases short-term change overhead, requiring agencies to balance reduced manual work against the cost of discovery, mapping, and phased migration. There is no universal standard for this yet, so best practice is evolving around risk-based prioritisation rather than big-bang replacement.
Some environments need special handling. Public-facing services may require longer overlap windows to avoid client trust issues, while internal workloads can often move faster if they already use automation and policy-as-code. Offline or air-gapped networks may still need local certificate authorities, but they should follow the same lifecycle logic: inventory, scoped issuance, defined expiry, and explicit revocation paths. Where agencies use hardware security modules or strict hardware-backed key storage, migration planning must also account for key export limits and vendor lock-in.
The main exception is a legacy application that cannot tolerate intermediate trust changes or modern automation hooks. In those cases, agencies should preserve the existing CA path, wrap it with monitoring, and modernise the surrounding governance first. The goal is operational reduction without authentication disruption, not forcing every platform into the same target state on day one.
Standards & Framework Alignment
This section maps relevant standards and security frameworks to the operational risks and controls described in this guidance.
OWASP Non-Human Identity Top 10 address the attack and risk surface, while NIST CSF 2.0 and NIST CSF 2.0 set the governance and control requirements practitioners need to meet.
| Framework | Control / Reference | Relevance |
|---|---|---|
| OWASP Non-Human Identity Top 10 | NHI-03 | Covers lifecycle rotation and revocation for machine identities. |
| NIST CSF 2.0 | PR.AC-1 | Supports controlled identity proofing and access enforcement for services. |
| NIST CSF 2.0 | PR.PT-1 | Protective technology guidance fits secure PKI automation and trust management. |
Use automated controls to reduce manual certificate handling and keep trust paths intact.
Related resources from NHI Mgmt Group
- Why is it crucial to adopt new authentication methods in MCP usage?
- How should NHS security teams reduce privileged access risk without disrupting clinical operations?
- How should security teams reduce vault sprawl without disrupting delivery?
- How should security teams phase out password-based authentication without disrupting operations?
