Authentication is not Authorization: Why treating them as the same breaks your security model

Authentication: Who are you?

Authentication is the process of verifying the identity of an entity — whether that’s a human or a non-human such as a service, a workload or an AI Agent. It answers a single question:
“Who is making this request?”

Before an entity can authenticate itself, its identity needs to be established and verified and it is given a credential (token, certificate or secret). When it later presents the credential as proof that its identity was verified, it is authenticating. 

In building terms, an employee badge let’s you identify an employee. An employee presents the badge to authenticate themselves. Knowing who the employee is, is separate from knowing if they are allowed into the building.

This is a critical distinction, authentication does not imply permission — it only proves identity. 

Authorization: What are you allowed to do?

Authorization is the decision about what an entity is allowed to do after (or sometimes even without) authentication. It answers the question:
“Given what we know about this entity, can it perform this action?”

Back to the building, a badge identifies an employee. When they present the badge, it opens their office door, but not the server or HVAC room. Access is controlled based on policies based on their identity and the door readers enforce that policy. The decision about who they are and what they can do are decoupled.

Why Authentication Alone Is Not Enough

In the building access example, requiring only authentication is equivalent to letting anyone with an employee badge access every room in every building, whether they need to be in that room or not, the very definition of overly broad access.

The same applies to digital systems. Where things go wrong is when systems treat authentication as sufficient for authorization, assuming that if an entity can authenticate, it should be allowed access. 

Equating authentication with authorization can be catastrophic. In its most extreme form, it creates equivalent access as long as you can authenticate. It enables lateral moves where an attacker manages to authenticate using stolen credentials in one system, and then access another system that accepts those authentication credentials. History is littered with examples like SolarWinds (2020), the Snowflake Customer Data Breach (2024) and Mercedes-Benz Supply Chain Attack (2024) where lateral moves and absence of additional fine grained authorization played a major role.

Deploying additional identity based authorization policies mitigates against these kinds of lateral moves by minimizing the blast radius when authentication credentials are compromised. It also creates additional audit trails and brings visibility that is necessary for governance. 

For modern security models, especially zero trust architectures, you need both:

• Authentication: to establish identity
• Authorization: to define and enforce access policies based on that identity

Only then can you:

• Apply fine-grained access controls per entity or per role
• Enforce least privilege
• Maintain audit trails showing who accessed what, when, and why
• Detect and respond to abuse tied to specific identities
• Revoke access safely and selectively

The Hidden Risk of Skipping Non-HumanWorkload Identity

One particularly dangerous side effect of conflating authentication with authorization is the decision not to assign identities to all non-human actors such as AI agents, application and workloads.

This often stems from the flawed assumption that “if something can’t authenticate, it can’t access anything.” In theory, this sounds like a security control but, in practice, it’s a massive blind spot.

Here’s why:

• Access paths often still exist via misconfigured network rules, shared credentials, default permissions, or ambient trust. Just because a workload doesn’t explicitly authenticate doesn’t mean it can’t interact with other systems.
• Unidentified workloads are unauditable. If a workload doesn’t have an identity and it is not authenticating itself, you can’t apply authorization policies based on its attributes, and you can’t tell who did what in your system.
• Rogue or compromised workloads love identity gaps. Without identity, there’s no accountability, no way to trace actions, and no way to revoke access.

Workloads that don’t have an identity should be considered rogue.

If you’re serious about building secure systems — especially in environments with dynamic infrastructure, microservices, or multi-cloud workloads — your baseline assumption must be:

Every workload gets an identity. Authorization only happens in the context of identity.

That’s how you enforce zero trust. That’s how you prevent lateral movement. That’s how you shrink the blast radius and catch bad behavior early.

In Summary

• Authentication verifies who you are.
• Authorization determines what you’re allowed to do.
• You can authorize without authentication (e.g. anonymous access), but not securely in high-trust systems.
• Conflating authentication and authorization leads to serious security risks.
• Every workload must have an identity — because identity is the foundation for meaningful authorization.
• Authentication is not enough. It’s the start of the story — not the end.