Authentication and Authorization: Different Roles in API Protection

Authentication Establishes Identity

Authentication is the process of confirming the identity connected to a request. The API needs a reliable way to associate incoming activity with a known user, service, or account.

During a security review, learners can examine several questions:

• How is the identity presented?
• How does the API confirm that identity?
• What happens when the identity information is missing?
• What happens when it is no longer valid?
• How are failed identity checks recorded?
• Does the error response reveal unnecessary details?

The review should also consider where authentication occurs. Some systems check identity at a central entry point, while others repeat checks within connected processes. The structure depends on the system, but the intended behavior should be clearly documented.

Identity status also matters. An account may be active, suspended, removed, or waiting for review. A previously accepted identity should not automatically remain valid after its account status changes.

Authorization Defines Permitted Actions

After identity is confirmed, the API must decide whether the requester may perform the action. This is authorization.

Authorization can depend on several factors:

• Assigned role
• Record ownership
• Account status
• Resource type
• Requested action
• Workflow stage
• Relationship to another user
• Current record state

A broad role name is rarely enough to describe the complete rule. For example, an editor may be allowed to update a draft but not a published record. An administrator may manage account settings but still be restricted from viewing private information outside her assigned area.

Clear authorization rules should describe the action, resource, and conditions together.

Why Route-Level Checks May Be Incomplete

A route may require a valid identity and still contain an authorization weakness. This can happen when the API confirms that a user is signed in but does not verify whether the requested record belongs to that user.

Consider a route that updates a profile record. The user may provide a record identifier in the request. If the API checks only that the user is authenticated, she may be able to submit the identifier of another record. A separate ownership check is needed before the update is processed.

This type of review is often called object-level authorization. It examines whether the requester may act on the specific record involved, not only whether she may use the route in general.

Build a Permission Matrix

A permission matrix is a useful way to document authorization rules. Roles are listed across one side, while actions appear along the other.

For example:

• View own record
• Update own record
• View shared record
• Update shared record
• Change account settings
• Change another user’s role
• Remove a record

Each cell describes whether the action is allowed, denied, or allowed only under stated conditions.

A permission matrix helps teams find unclear areas. It can reveal that one action has no documented owner, two roles have overlapping responsibilities, or a route behaves differently from the written requirement.

The matrix should include conditional rules. A simple “allowed” label may not be enough when permission depends on ownership, account status, approval state, or a relationship between records.

Review Multi-Stage Workflows

Authorization decisions may need to occur more than once. A workflow can begin with a permitted action and later move into a stage with different requirements.

For example, a user may submit a record, another role may review it, and a third role may approve a status change. Each stage involves a different action and responsibility.

The API should not rely only on the permission decision made at the beginning. It should review the current requester, current record state, and current action at each protected stage.

This is especially important when workflows involve shared resources or ownership changes. A person who created a record may lose permission after it is transferred. A role that could view a draft may not be allowed to view private comments added during review.

Examine Responses as Part of Authorization

Authorization does not apply only to actions. It also affects returned information.

A user may be allowed to view a record while still being restricted from seeing certain fields. The API response should match the user’s role and the purpose of the request.

A response review can examine:

• Which fields are returned?
• Are all returned fields required?
• Do different roles receive different information?
• Are private fields removed when not needed?
• Do error messages reveal whether a protected record exists?

Field-level response rules can be documented alongside the permission matrix. This creates a clearer connection between actions and information exposure.

Document Decisions Clearly

Authentication and authorization rules should be written in direct, specific language. Statements such as “users have appropriate permissions” are too broad for careful review.

A clearer statement might describe that an active account holder may update her own contact record after identity confirmation and ownership review. Another rule may state that only a designated administrative role may change account status, and that the action should be recorded.

Clear documentation supports development, review, testing, and later updates. It also helps learners understand that API protection is built through a sequence of defined decisions.

Authentication establishes who is making the request. Authorization determines what that identity may do. Treating these as separate but connected responsibilities provides a stronger foundation for reviewing API behavior.