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Category: Identity & Access

Authentication and Authorization

Also known as: AuthN/AuthZ, AuthN and AuthZ, Identity Verification and Access Control

Simply put

Authentication is the process of confirming that a user or device is who or what it claims to be, while authorization is the process of determining what an authenticated user or device is permitted to access or do. In simple terms, authentication answers "who are you?" and authorization answers "what are you allowed to do?" The two are distinct but complementary steps, and authentication generally must occur before authorization can be applied.

Formal definition

Authentication (AuthN) is the verification of the asserted identity of a person, device, or entity, typically achieved by validating credentials or other proof of identity. Authorization (AuthZ) is the subsequent determination of the permissions, entitlements, or level of access that the authenticated principal holds over specific system resources. These are separate functions and should not be conflated: successful authentication establishes identity but confers no access rights on its own, whereas authorization governs access decisions and presupposes that identity has already been established. Specific implementation mechanisms, protocols, and policy models vary by system and are out of scope for this definition.

Why it matters

Authentication and authorization are foundational to access control, and confusing the two is a common source of security weaknesses. Because authentication only establishes identity while authorization governs what that identity may do, treating a successful login as if it also granted broad access can lead to over-permissioned accounts and unintended exposure of resources. Keeping the two functions distinct allows an organization to verify identity rigorously while still constraining what any given user or device is permitted to access.

For compliance purposes, the distinction matters because many data protection and information security obligations turn on the ability to demonstrate both who accessed a resource and whether that access was permitted. Verifying identity without enforcing appropriate access limits, or granting access without reliably confirming identity, can leave gaps that undermine accountability. Where these controls are relevant to regulated data or systems, the specific requirements depend on the applicable legal or contractual framework, the sensitivity of the data, and the organization's risk profile, and readers should verify obligations against the current authoritative source for their jurisdiction and sector.

This entry defines the two concepts and their relationship at a general level. It does not address specific authentication factors, authorization models, protocols, or any particular certification or regulatory requirement, and application to a given system requires professional judgment based on the facts involved.

Who it's relevant to

Information Security Professionals

Security teams design and operate the controls that verify identity and enforce access decisions. Keeping authentication and authorization distinct helps them avoid over-permissioned accounts and ensure that confirming who a user is does not by itself grant access to resources.

Auditors and Assessors

Those reviewing access controls generally need to evaluate both whether identity is reliably verified and whether permitted access is appropriately constrained. Understanding the separation between the two functions supports clearer findings about where a control gap, if any, actually lies.

Data Protection and Privacy Specialists

Where access to regulated or sensitive data is at issue, the ability to confirm both the identity of a user and whether their access was permitted supports accountability. Specific obligations depend on the applicable framework, data category, and jurisdiction, and should be verified against the current authoritative text.

Legal Counsel and Compliance Officers

Counsel and compliance staff mapping controls to obligations benefit from distinguishing identity verification from access control, since the two may satisfy different requirements. Application to a specific regulatory or contractual context requires professional judgment based on the facts.

Inside AuthN/AuthZ

Authentication

The process of verifying that an entity (a user, device, or service) is who or what it claims to be. Authentication answers the question of identity and typically relies on one or more factors: something the entity knows (a password or PIN), something it has (a token or smart card), or something it is (a biometric characteristic). It establishes identity but does not, by itself, determine what the authenticated entity may do.

Authorization

The process of determining what an authenticated entity is permitted to do—which resources it may access and which actions it may perform. Authorization operates after authentication and enforces access decisions against defined permissions, roles, or policies. An entity may be authenticated yet still be denied access to particular resources through authorization controls.

Multi-Factor Authentication (MFA)

An authentication approach that requires an entity to present two or more independent factors from distinct categories (knowledge, possession, inherence). MFA is intended to reduce the likelihood that a compromised single factor grants access. It is widely recommended in security frameworks and, in some sectors or jurisdictions, may be expected or required for certain data or systems—readers should verify specific obligations against the applicable rule.

Access Control Models

Structured approaches to expressing authorization decisions, such as role-based access control (RBAC), which assigns permissions to roles held by users, and attribute-based access control (ABAC), which evaluates attributes of the subject, resource, and context. The choice of model affects how granularly and dynamically permissions can be managed.

Least Privilege

A principle applied within authorization whereby entities are granted only the access necessary to perform their functions, and no more. It limits the scope of potential misuse or compromise but is a design and operational principle rather than a single technical control.

Identity and Credential Management

The lifecycle activities supporting authentication and authorization, including provisioning identities, issuing and rotating credentials, and revoking access when it is no longer needed. Weaknesses in this lifecycle—such as orphaned accounts or unrotated credentials—can undermine otherwise sound authentication and authorization controls.

Common questions

Answers to the questions practitioners most commonly ask about AuthN/AuthZ.

Are authentication and authorization just two names for the same access control step?

No. They are distinct functions that are often performed in sequence but should not be conflated. Authentication establishes who or what an entity is (verifying a claimed identity), while authorization determines what an authenticated entity is permitted to do (which resources or actions are allowed). An entity can be successfully authenticated yet still be denied access to a particular resource because authorization is evaluated separately. Treating them as one concept tends to obscure failure points, since a system may correctly verify identity while applying flawed permission logic, or vice versa.

Does adding multi-factor authentication mean my authorization is also handled?

No. Multi-factor authentication strengthens the identity-verification step by requiring additional evidence, but it says nothing about what the verified entity is permitted to do afterward. Authorization decisions—such as role assignments, least-privilege enforcement, and resource-level permissions—operate independently of how strongly the identity was established. A strongly authenticated user can still hold excessive or misconfigured privileges. The two controls address different risks and generally need to be designed, tested, and reviewed separately.

How do we decide between role-based and attribute-based authorization models?

The choice generally depends on the granularity, context-sensitivity, and scale of the access decisions you need to make. Role-based approaches assign permissions to defined roles and tend to be simpler to administer where access patterns are relatively stable. Attribute-based approaches evaluate characteristics of the user, resource, action, and environment, which can support finer-grained or context-dependent decisions at the cost of greater design and governance complexity. Many organizations use a hybrid. The appropriate model is fact-specific and should be assessed against your risk profile, resource sensitivity, and administrative capacity; this entry does not prescribe a particular model for any given environment.

Where should authorization logic be enforced in a system architecture?

As a general principle, authorization should be enforced at trusted points that the client cannot bypass—typically server-side or at a policy enforcement point—rather than relying solely on controls presented in a user interface. Distributed and microservice architectures often centralize policy decisions while enforcing them at multiple points. The specific placement depends on your architecture, threat model, and integration constraints, and involves professional judgment. This entry describes the concept and does not endorse a specific enforcement design.

How often should access rights and permissions be reviewed?

Periodic review of granted permissions is a widely recognized practice intended to detect privilege accumulation, stale accounts, and misconfigured access. The appropriate frequency and rigor generally depend on risk level, data sensitivity, regulatory context, and organizational size, and any specific cadence may be driven by applicable obligations or contractual commitments rather than by this definition. Where a particular framework or regulation applies to you, verify the review expectations against the current authoritative source.

How do authentication and authorization relate to logging and audit requirements?

Authentication and authorization events are commonly among the activities organizations record to support accountability and investigation, but the concepts themselves are distinct from logging. Authentication and authorization control access, whereas logging and audit trails create a record of access decisions and actions for later review. What must be logged, how long records are retained, and how they are protected are typically governed by separate policy, contractual, or regulatory requirements that vary by jurisdiction and sector. Confirm any specific logging obligations against the applicable current requirements rather than assuming a universal standard.

Common misconceptions

Authentication and authorization are the same thing, or the terms can be used interchangeably.

They are distinct and sequential concepts. Authentication verifies identity; authorization determines what the verified identity may do. A system can authenticate an entity successfully and still deny it access to specific resources. Conflating the two obscures where a control failure actually occurs.

Enabling multi-factor authentication satisfies access control requirements on its own.

MFA strengthens authentication—the identity-verification step—but does not address authorization. Without properly scoped permissions and least-privilege enforcement, a strongly authenticated user may still hold excessive access. MFA and authorization controls address different risks and generally need to be implemented together.

Implementing authentication and authorization controls means an organization is compliant with applicable regulations.

These controls are technical and organizational measures that may support compliance, but implementing them is not the same as demonstrating compliance or achieving certification. Whether specific controls are required, and to what degree, depends on the applicable regulation, framework, sector, and risk context, which differ across jurisdictions and should be verified against current authoritative sources.

Best practices

Treat authentication and authorization as separate design concerns, documenting how identity is verified and, separately, how access decisions are made and enforced for each system.

Apply the principle of least privilege, granting only the access necessary for a function and reviewing entitlements periodically to identify and remove excessive or unused permissions.

Use multi-factor authentication for access to sensitive systems and data where appropriate, and verify whether any applicable sector or jurisdictional rule expects or requires it rather than assuming a universal standard.

Manage the full identity and credential lifecycle, including timely provisioning, credential rotation, and prompt revocation of access when it is no longer needed, to prevent orphaned accounts.

Select an access control model (such as RBAC or ABAC) suited to the organization's scale and the granularity of access decisions required, and document the rationale.

Verify specific control requirements against the current text of the applicable regulation, framework, or contractual obligation, recognizing that these are periodically amended and that application to particular circumstances requires professional judgment.