Securing IBM i APIs at a Beginner Level

Learning Objective

By the end of this lesson, you will be able to explain, at a beginner level, what authentication, authorization, HTTPS, and least privilege mean for an IBM i API, without needing to implement any of them in depth yet.

Simple Explanation

Securing an API rests on a few core ideas, each of which already has a familiar counterpart on IBM i:

• Authentication answers "who is calling?" Similar to signing on to IBM i with a user profile and password, an API caller needs to prove its identity in some way before being trusted.
• Authorization answers "what is this caller allowed to do?" This is the same idea already covered in the Authorities and Object Access Basics lesson: being authenticated does not automatically mean being allowed to do everything.
• HTTPS means the connection between the caller and the API is encrypted, so data traveling between them cannot be easily read by someone intercepting it along the way.
• Secrets are values like passwords or API keys that prove identity and must be kept private, never hardcoded into source code or written into a log file.
• Least privilege means giving a caller only the specific access it actually needs, not broad access "just in case," the same principle already familiar from assigning object authorities carefully rather than granting *ALL everywhere.

Why It Matters

An API that exposes real business logic is also exposing a new way to reach that logic from outside the system. Without authentication, any caller could pretend to be anyone. Without authorization, an authenticated caller could potentially do more than intended. Without HTTPS, data in transit could be exposed. Applying these ideas deliberately is what keeps an exposed API as safe as the traditional, tightly controlled ways of reaching IBM i logic already covered elsewhere in this course.

Practical Example

Imagine the customer validation API introduced earlier in this batch. A responsible design confirms the caller's identity first (authentication), checks that this specific caller is allowed to check customer numbers at all (authorization), ensures the connection is encrypted (HTTPS) so the customer number is not exposed in transit, and grants that caller only the ability to check customer numbers, not broader access to unrelated customer data (least privilege).

This is a simplified, illustrative example rather than a specific real security implementation, but it reflects the core ideas every IBM i API should account for, even at a beginner level.

Common Confusions

"Are authentication and authorization the same thing?" No. Authentication confirms who is calling. Authorization decides what that caller is allowed to do. A caller can be authenticated but still not authorized for a specific action, the same distinction already covered by the 401 versus 403 status codes.

"Do I need to implement OAuth or JWT to understand this lesson?" No. This lesson stays at the conceptual level: what authentication, authorization, HTTPS, secrets, and least privilege mean and why they matter. Specific implementation technologies are a deeper topic beyond this introductory lesson.

"Isn't it easier to just grant broad access to avoid access problems?" It might seem easier short-term, but it directly violates least privilege and increases the damage a compromised caller or a mistake could cause. Granting only what is actually needed is the safer default, exactly as it already is for native object authorities.

Quick Recap

• Authentication confirms who is calling; authorization decides what they are allowed to do.
• HTTPS keeps data encrypted while traveling between caller and API.
• Secrets, such as passwords or API keys, must be kept private and never hardcoded or logged.
• Least privilege means granting only the specific access actually needed, the same principle already familiar from object authorities.

Try Asking the AI Tutor

Use the AI Tutor to ask follow-up questions about this lesson. For example, try asking:

• "How does the 401 versus 403 status code distinction connect to authentication versus authorization?"
• "Can you give me an example of a least-privilege mistake that might seem convenient at first but causes problems later?"