# NIST SP 800-53 Rev. 5 IA-5(2) — Public Key-Based Authentication - Source: https://support.icompaas.com/compliance/nist-sp-800-53-rev-5/ia-5-2-public-key-based-authentication - Section: [Compliance](https://support.icompaas.com/compliance) › [NIST SP 800-53 Rev. 5 Controls](https://support.icompaas.com/compliance/nist-sp-800-53-rev-5) › IA — Identification and Authentication - Last updated: 2026-06-05 - Publisher: iCompaas, Inc. (https://www.icompaas.com) **NIST SP 800-53 Rev. 5**·Control `IA-5(2)`·high·Component: **Identification and Authentication** ## What this control requires > Control mandates enforcing authorized access to private keys, mapping authenticated identities to accounts, and, when using PKI, validating certificates by verifying certification paths to a trust anchor and checking status information. It also requires implementing a local cache of revocation data to support path discovery and validation. This control supports the Public Key Infrastructure (PKI) System capability within the Identification and Authentication family. > > — NIST SP 800-53 Rev. 5, Control IA-5(2) ### In plain English Control mandates enforcing authorized access to private keys, mapping authenticated identities to accounts, and, when using PKI, validating certificates by verifying certification paths to a trust anchor and checking status information. In practice, this means you can prove you access management-level controls on a defined cadence. ## Why it matters SP 800-53 is the catalogue every U.S. federal authorisation (FedRAMP, FISMA, CMMC) and most regulated industries point at. A missing control surfaces as a Plan of Action & Milestones (POA&M) item that an Authorizing Official must approve before the Authority To Operate is granted or renewed. This control is rated **high**. Auditors expect a named owner, a remediation SLA, and a tooling artefact that evidences continuous operation. ## What an auditor looks for A 3PAO (FedRAMP) or Independent Assessor (NIST RMF) tests against NIST SP 800-53A assessment procedures. For each control they expect a documented implementation that addresses every assessment objective (Examine, Interview, Test) and an implementation summary in the System Security Plan. Within **Identification and Authentication**, the assessor will trace your implementation back to the catalogue reference (Control IA-5(2)) and look for objective evidence on the latest two assessment cycles. ## How to implement 1. Write a short policy stating intent, scope and named owner. 2. Encode it as a platform guardrail — SCP, Azure Policy initiative, Organisation Policy, or repository policy. 3. Wire a monitoring signal that catches drift (CSPM rule, SIEM rule, scheduled query, Workspace alert) and ticket it. 4. Review on a documented cadence and capture the review in the risk register or compliance tracker. ### Operational checklist - **Access.** Document the trigger, the owner and the cadence. - **Revocation.** Document the trigger, the owner and the cadence. - **Information.** Document the trigger, the owner and the cadence. - **Data.** Document the trigger, the owner and the cadence. - **Validation.** Document the trigger, the owner and the cadence. - **Scope:** management, accounts, information, authentication, system, identity, review, capability. ## Evidence to collect - **Identity Scan.** IAM / IdP exports — Entra ID, Okta, IAM Identity Center, Workspace directory — showing accounts, roles, MFA state and last sign-in. Identity analytics (Okta, SailPoint, Access Analyzer) demonstrates least-privilege. Focus: Public Key-Based Authentication. ## How it maps to other frameworks Computed from shared tags, control component and key-operation subjects — handy when you are reconciling controls across an audit. - [**NIST SP 800-171 Rev. 3 3.5.5** — Identifier Management](https://support.icompaas.com/compliance/nist-sp-800-171-rev-3/3-5-5-identifier-management) - [**CIS Controls v8 9.2** — Use DNS Filtering Services](https://support.icompaas.com/compliance/cis-controls-v8/9-2-use-dns-filtering-services) - [**ISO/IEC 27001:2022 A.5.2** — Information security roles and responsibilities](https://support.icompaas.com/compliance/iso-27001-2022/a-5-2-information-security-roles-and-responsibilities) - [**BSI C5:2020 IDM-08** — Confidentiality of authentication information](https://support.icompaas.com/compliance/bsi-c5-2020/idm-08-confidentiality-of-authentication-information) - [**ISO/IEC 27701:2025 A.3.8** — Identity management](https://support.icompaas.com/compliance/iso-27701-2025/a-3-8-identity-management) ## Related controls in NIST SP 800-53 Rev. 5 - [**Control IA-2(10)** — Single Sign-On](https://support.icompaas.com/compliance/nist-sp-800-53-rev-5/ia-2-10-single-sign-on) - [**Control IA-2(3)** — Local Access To Privileged Accounts](https://support.icompaas.com/compliance/nist-sp-800-53-rev-5/ia-2-3-local-access-to-privileged-accounts) - [**Control IA-2(4)** — Local Access To Non-Privileged Accounts](https://support.icompaas.com/compliance/nist-sp-800-53-rev-5/ia-2-4-local-access-to-non-privileged-accounts) - [**Control IA-4** — Identifier Management](https://support.icompaas.com/compliance/nist-sp-800-53-rev-5/ia-4-identifier-management) - [**Control IA-12(3)** — Identity Evidence Validation And Verification](https://support.icompaas.com/compliance/nist-sp-800-53-rev-5/ia-12-3-identity-evidence-validation-and-verification) - [**Control IA-2(1)** — Multi-Factor Authentication To Privileged Accounts](https://support.icompaas.com/compliance/nist-sp-800-53-rev-5/ia-2-1-multi-factor-authentication-to-privileged-accounts) ## References - [NIST Computer Security Resource Center — NIST SP 800-53 Rev. 5](https://csrc.nist.gov/Projects/risk-management/sp800-53-controls) - Catalogue identifier: `Control IA-5(2)` Topics: identity accessidentity managementaccess reviewcertificate managementprivileged access ## Related compliance guidance - [NIST SP 800-53 Rev. 5: a practical implementation guide for cloud teams](https://support.icompaas.com/compliance/nist-sp-800-53-rev-5): Start with the full NIST SP 800-53 implementation guide — scope, roadmap, evidence and how the assessment runs. - [NIST SP 800-171 and CMMC: a practical guide to protecting CUI in the cloud](https://support.icompaas.com/compliance/nist-sp-800-171-rev-3): If your obligation is protecting CUI in your own systems for a federal or defence contract, this derived subset — not the full catalogue — is the requirement. - [SOC 2 compliance: a practical implementation guide for cloud-native SaaS teams](https://support.icompaas.com/compliance/soc-2-trust-services-criteria): Most commercial SaaS already hold a SOC 2 Type 2, and FedRAMP 20x Class A is designed for providers that have one.