Common Identity Model

Expanded Definition

A common identity model is not just a naming convention. It is a governance pattern that normalises users, non-human identities, and autonomous agents under one policy plane so ownership, authentication strength, entitlement review, and lifecycle actions are handled consistently. In practice, that means a service account, API key, workload identity, and AI Agent are managed as first-class identities rather than exceptions.

Usage in the industry is still evolving, and definitions vary across vendors, especially where agentic AI and machine-to-machine authentication overlap. The safest interpretation is to anchor the model in policy consistency: one identity source of truth, one approval path, and one review cadence, even when the credential type differs. That approach aligns with the direction of NIST Cybersecurity Framework 2.0, which emphasises governance, access control, and continuous oversight.

The most common misapplication is treating common identity model as a directory consolidation project, which occurs when teams merge records without unifying ownership, privilege review, and offboarding logic.

Examples and Use Cases

Implementing a common identity model rigorously often introduces integration overhead, requiring organisations to weigh consistent governance against the effort of normalising legacy systems and tool-specific identity formats.

• A platform team maps human admins, CI/CD service accounts, and deployment Agents into the same review workflow so Ultimate Guide to NHIs principles can be applied uniformly across identity classes.
• A security team applies one entitlement review standard to SaaS users and machine identities, then cross-checks high-risk access patterns against the breach patterns described in 52 NHI Breaches Analysis.
• An engineering org governs secrets, certificates, and workload identities through a common approval path, then aligns access policy with NIST Cybersecurity Framework 2.0 and least-privilege expectations.
• A cloud team uses one offboarding process for employees and retired automation jobs so stale permissions do not survive after application migration or pipeline decommissioning.
• An AI governance team treats an autonomous agent with tool access as an identity object, requiring the same ownership, logging, and revocation discipline as any privileged service account.

In environments with heavy CI/CD, a common identity model is most useful when ownership changes frequently and no single team can safely manage exceptions by hand.

Why It Matters in NHI Security

Common identity models reduce fragmentation, and fragmentation is where NHI risk compounds. When users, NHIs, and Agents are governed separately, teams often miss shared attack paths such as credential reuse, orphaned access, and inconsistent rotation. That creates blind spots in reviews, especially when Secrets live outside approved vaults or when workloads inherit privileges that no owner actively tracks. NHIMG research shows that only 5.7% of organisations have full visibility into their service accounts, which means most environments are already operating with incomplete identity inventory.

This is why the concept matters to operational security, not just architecture. A unified model makes it easier to enforce ZTA principles, apply JIT access, and support Zero Standing Privilege across mixed identity types. It also helps translate guidance from Top 10 NHI Issues into a concrete control structure, rather than a collection of disconnected fixes. The best practice is to pair identity unification with Ultimate Guide to NHIs — What are Non-Human Identities for lifecycle and governance context.

Organisations typically encounter the need for a common identity model only after a breach review, audit failure, or credential incident reveals that no one can prove who owned a machine identity when access was granted.

Related resources from NHI Mgmt Group

• Non-Human Identity Access Management
• Overprivileged Identity
• Shared Responsibility Model
• What is the difference between model security and agent identity controls?