Securing APIs with Azure AD and API Management: The Gatekeeper and the Bouncer Approach

 Imagine you have a company that built 20 web APIs (think of them like magic tools that do special tasks when they are asked). The company is now creating 10 new web apps (websites or apps) that will use those special APIs.

The company wants to make sure that only those 10 web apps can use the special APIs. If some other app or person who isn't allowed tries to use them, it should be blocked.

To do this, they want to:

1. Check who is asking (like how you would use a special key to unlock a door).
2. Use Azure Active Directory (Azure AD) to make sure the requests (like knocking on the door) are valid.
3. Minimize effort: They don’t want to spend too much time setting this up and managing it.

The Requirements:

• Block unauthorized requests: Don’t let people who don’t have the key get access to the APIs.
• Use Azure AD-generated claims: Claims are like badges in a digital world that prove who you are.

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Answer Explanation

1. Grant Permissions to Allow the Web Apps to Access the Web APIs

The first part asks how to give permission to the 10 web apps so they can use the 20 web APIs. You need to decide who should give this permission:

• Azure AD: This is like the gatekeeper that decides who can come in.
• Azure API Management: This manages how APIs are shared and used.
• The Web APIs: These are the special tools that do the work.

The correct answer is Azure AD because it helps make sure that only the right people (the 10 web apps) get permission to access the APIs, just like a gatekeeper checking who has the key.

2. Configure a JSON Web Token (JWT) Validation Policy

The second part asks how to verify the identity of someone using the APIs. A JWT (JSON Web Token) is like a special ID card in the digital world that proves who you are. You need to decide who should check this ID:

• Azure AD: It checks who you are and gives you the ID card (JWT).
• Azure API Management: It helps manage and protect the APIs.
• The Web APIs: The tools that do the work.

The correct answer is Azure API Management because it can take the ID card (JWT) and check if it's real, making sure that only the right apps use the APIs.

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Final Answer

• Grant permissions to allow web apps to access the web APIs by using: Azure AD
• Configure a JSON Web Token (JWT) validation policy by using: Azure API Management

In Simple Terms:

• Azure AD is like the gatekeeper that gives special permission to the apps to use the APIs.
• Azure API Management is like the security guard that checks the special ID (JWT) and makes sure the person trying to use the APIs is who they say they are.

This way, the company makes sure only the right apps can use their magic APIs without too much work.

What are Claims?

In simple terms, claims are bits of information or statements about a user that a service (like Azure Active Directory) generates to help other applications (like web apps or APIs) know who the user is and what permissions they have. Claims can be things like:

• Who the user is (like their username or email address).
• What groups they belong to (like being part of the "Admins" or "Developers" group).
• What roles they have (like "Editor" or "Viewer").

How are Claims Generated?

Claims are generated during the authentication process when a user or app signs into a system (like Azure Active Directory (Azure AD)) and requests access to another app or API. Here's how it works step-by-step:

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Step-by-Step Explanation of How Claims are Generated:

1. User or App Tries to Log In:

   • Imagine you (the user) or an app wants to log into a system like a web app or an API.
   • You enter your credentials (like your username and password), or an app uses its credentials (like a certificate or secret).

2. Azure AD Verifies the Identity:

   • Azure AD checks if the username and password (or app credentials) are correct.
   • If they are correct, Azure AD verifies the identity of the user or app.

3. Azure AD Creates a Token:

   • Once Azure AD knows who you are, it creates a token (like a secure digital document). This token contains claims.
   • A token can be a JWT (JSON Web Token), which is often used for web apps and APIs.

4. Claims are Added to the Token:

   • Azure AD adds claims to the token. These claims include information about the user or app, like:
     • Name (who is the user).
     • Email (contact information).
     • Roles (what the user is allowed to do).
     • Groups (what teams the user belongs to).

5. Token with Claims is Sent to the App or API:

   • After generating the token with claims, Azure AD sends this token to the app or API that the user is trying to access.
   • This token acts like a passport that proves who the user is and what they are allowed to do.

6. App or API Reads the Claims:

   • The app or API receives the token and looks at the claims to decide:
     • Whether to allow or deny access.
     • What permissions the user or app should have (like "read-only" or "full access").

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Example:

Let’s say you’re logging into a web app that manages vacation requests. Here's what might happen:

1. Login: You try to log into the web app by entering your username and password.

2. Azure AD Generates Claims:

   • Azure AD checks if your login is correct.
   • It creates a token and adds claims like:
     • Name: "John Doe"
     • Email: "john.doe@example.com"
     • Role: "Manager"

3. Web App Receives Claims:

   • The web app looks at the token, reads the claims, and sees that you are John Doe and that you have the role of Manager.

4. Access Granted:

   • Since the app sees that you are a Manager, it allows you to access special features, like approving vacation requests.

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Why are Claims Important?

• Security: Claims help verify who is accessing a system and what they are allowed to do.
• Personalization: Apps can use claims to show content specific to a user (e.g., showing a manager extra options).
• Simplifies Authentication: Instead of asking the app to verify a user's identity directly, it trusts Azure AD to generate claims and tokens.

Conclusion:

Claims are small pieces of information created by Azure AD during the authentication process. They help apps and APIs understand who the user is, what roles they have, and what permissions they should be given

What is a JWT (JSON Web Token) in This Scenario?

In this scenario, a JWT (JSON Web Token) is a secure digital token that Azure Active Directory (Azure AD) creates after successfully verifying the identity of a user or application. The JWT contains claims (information about the user or app) that prove who the user or app is, and it is used to authorize access to the web APIs.

Think of a JWT as a digital passport that a user or app presents when trying to access a resource (like an API). The API reads the JWT to decide whether the user or app should be allowed access.

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How Does JWT Work in This Scenario?

Let's break it down in simple terms:

1. User or App Logs In:

   • The user or app wants to access one of the 20 web APIs.
   • They first go through Azure AD to log in, using their credentials.

2. Azure AD Creates a JWT:

   • Once Azure AD verifies that the user or app is legitimate (authentication), it generates a JWT.
   • The JWT contains claims, which include information like:
     • Who the user or app is (e.g., username, roles).
     • Permissions (what the user or app is allowed to do).
     • Issuer (who created the token, in this case, Azure AD).

3. JWT is Sent to the Web App or API:

   • After creating the JWT, Azure AD gives the token to the web app or API that the user or app is trying to access.
   • The web app or API now has the user's digital passport in the form of a JWT.

4. The API Validates the JWT:

   • The API uses Azure API Management to validate the JWT. This means it checks:
     • Whether the JWT is real (issued by Azure AD).
     • Whether the token has expired or is still valid.
     • What permissions the user or app has (based on the claims inside the JWT).

5. Access is Granted or Denied:

   • If the JWT is valid and contains the right claims, the API allows the user or app to access its resources.
   • If the JWT is not valid or the user does not have the correct claims, access is denied.

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Example: How JWT Works in the Scenario

Let’s say a user, John, is trying to access a web API that provides information on employee records.

1. Step 1: John Logs In

   • John tries to access the employee API. He is first directed to Azure AD to log in.

2. Step 2: Azure AD Creates a JWT

   • After verifying John’s identity, Azure AD creates a JWT. The JWT contains claims such as:
     • Name: John Doe
     • Role: HR Manager
     • Access Rights: Read access to employee records

3. Step 3: John Sends the JWT to the API

   • The JWT is sent to the employee API.
   • The API reads the JWT and sees that John has the role of HR Manager, which allows him to read employee records.

4. Step 4: The API Validates the JWT

   • The API validates the JWT, checking:
     • That it was issued by Azure AD.
     • That it hasn’t expired.
     • That John has the right role (HR Manager).

5. Step 5: Access Granted

   • Since everything checks out, the API allows John to see the employee records.

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Structure of a JWT

A JWT is made up of three parts, separated by dots (.):

1. Header: Contains metadata about the token, including the type of token (JWT) and the algorithm used to sign it.
2. Payload: Contains the claims (information about the user, roles, permissions, etc.).
3. Signature: Used to verify the token’s authenticity. The signature ensures that the token hasn’t been tampered with.

For example, a JWT might look like this:

eyJhbGciOiJIUzI1NiIsInR5cCI6IkpXVCJ9.eyJzdWIiOiIxMjM0NTY3ODkwIiwibmFtZSI6IkpvaG4gRG9lIiwicm9sZSI6IkhSIiwiZXhwIjoxNjAwMDAwMDAwfQ.SflKxwRJSMeKKF2QT4fwpMeJf36POk6yJV_adQssw5c

Each part:

• Header: eyJhbGciOiJIUzI1NiIsInR5cCI6IkpXVCJ9
• Payload: eyJzdWIiOiIxMjM0NTY3ODkwIiwibmFtZSI6IkpvaG4gRG9lIiwicm9sZSI6IkhSIiwiZXhwIjoxNjAwMDAwMDAwfQ
• Signature: SflKxwRJSMeKKF2QT4fwpMeJf36POk6yJV_adQssw5c

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Why Use JWT in This Scenario?

• Security: JWT tokens are signed, ensuring that they cannot be tampered with, and the claims they contain can be trusted by the web API.
• Efficiency: JWT is lightweight and can be passed between different systems or services. No need to check a central server after the token is issued.
• Authentication and Authorization: JWTs are used to both authenticate the user (verify who they are) and authorize their actions (check what they can do).

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Conclusion:

In this scenario, JWT (JSON Web Token) is used as a secure token that contains claims about the user or app. It allows the web APIs to verify the identity of the user or app and determine whether they have the right permissions to access the resources. Azure AD creates the JWT, and Azure API Management validates it before allowing access to the APIs.

Azure API Management (APIM) plays a crucial role in this scenario by acting as a gateway that securely manages, validates, and controls access to your web APIs. Let’s break down why APIM is important and where it fits in the overall architecture:

Why Azure API Management (APIM) is Involved:

1. Centralized Access Control and Security:

   • APIM sits between the web apps and the web APIs. It acts as a security gateway to ensure that only authenticated and authorized requests reach the APIs.
   • Without APIM, the web APIs would need to individually handle security checks, authentication, and validation of JWTs (JSON Web Tokens). This would increase complexity because each API would have to manage these tasks separately.
   • By using APIM, you can enforce security policies such as JWT validation consistently across all your APIs.

2. JWT Validation:

   • One of the key requirements in this scenario is to use Azure AD-generated claims and validate the JWT issued by Azure AD.
   • APIM has built-in capabilities to validate JWT tokens. It checks if the token is:
     • Issued by a trusted authority (in this case, Azure AD).
     • Not expired (checking the token’s expiration time).
     • Signed correctly (verifying the token’s signature).
   • APIM can easily verify that the JWT includes the correct claims (like user roles or permissions) and allow or deny access based on that.

3. Protection Against Unauthorized Access:

   • Without APIM, requests could potentially reach your web APIs, even if they’re unauthorized.
   • APIM blocks unauthorized or invalid requests before they even reach the APIs. This ensures that only valid, authorized requests (with proper JWT tokens) make it to your backend APIs.

4. Centralized Management and Simplified Configuration:

   • Using Azure API Management simplifies managing multiple APIs. Instead of configuring JWT validation and access control for each of the 20 web APIs separately, you can centralize these policies in APIM and apply them across all APIs.
   • This reduces the effort and complexity required to manage security across multiple APIs.

5. Monitoring and Analytics:

   • APIM also provides built-in features for monitoring, logging, and analytics. This means you can track all incoming requests, see how the APIs are being used, and identify any potential security issues or misuse of the APIs.
   • It gives you a detailed view of who is using the APIs and how they are being used.

Where APIM Fits in This Scenario:

1. User or App Requests Access to an API:

   • A web app or user sends a request to use one of the 20 web APIs.
   • The request first goes to Azure API Management (APIM), not directly to the APIs.

2. APIM Checks the JWT:

   • APIM checks if the request contains a JWT token issued by Azure AD.
   • APIM validates the JWT to ensure it is correct, not expired, and contains the right claims.

3. APIM Enforces Access Control:

   • Based on the JWT claims (like user roles or permissions), APIM decides whether the user or app is authorized to access the API.
   • If the JWT is valid, APIM forwards the request to the appropriate web API.
   • If the JWT is not valid or the user does not have the required permissions, APIM denies the request.

4. API Receives Authorized Requests:

   • Once APIM confirms the request is authorized, it sends the request to the backend web API, allowing the API to do its work without worrying about authentication or authorization.

Advantages of Using APIM in this Scenario:

• Centralized Security: APIM provides a single point where you can manage security and authentication for all your APIs. This is much simpler than configuring each API individually.

• JWT Validation: APIM validates JWTs issued by Azure AD, ensuring that only authenticated and authorized requests make it to the APIs.

• Policy Management: You can configure access policies (like rate-limiting, throttling, IP filtering) that apply to all your APIs via APIM.

• Scalability: As you add more web apps and APIs, APIM can scale easily, ensuring that security and access controls remain consistent across all your APIs.

• Monitoring and Analytics: APIM provides detailed analytics and monitoring of all API traffic, which helps with usage tracking, performance monitoring, and security audits.

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Conclusion:

Azure API Management (APIM) is essential in this scenario because it acts as the central security layer between the web apps and the web APIs. It:

• Validates the JWT tokens generated by Azure AD.
• Enforces access control and security policies.
• Simplifies the management of multiple APIs by centralizing security, logging, and monitoring.

By using APIM, the company can efficiently block unauthorized requests and manage security across all of their 20 web APIs without needing to configure each API individually.

if Azure AD is gatekeeper then who is APIM here

Azure AD is the gatekeeper, then Azure API Management (APIM) would be the security guard or bouncer

Here's how the analogy works:

Azure AD as the Gatekeeper:

• Azure AD checks who the user or app is when they knock on the door (log in).
• It gives them a special ID badge (a JWT token) that says who they are and what they are allowed to do.
• This ID badge contains claims that show the user's identity and permissions.
• Azure AD ensures that only authorized people get the badge.

APIM as the Security Guard (Bouncer):

• APIM is positioned between the user/app and the actual APIs. Think of it as a security checkpoint before users can access the APIs.
• APIM looks at the ID badge (JWT) that the user got from Azure AD.
• It checks the badge to make sure:
  • The badge is real (not fake, not expired).
  • The badge says the user is allowed to go inside and access the specific API.
• If everything looks good, APIM lets the user or app through to the APIs (gives them access to the API).
• If something is wrong with the badge or the user doesn't have the right permissions, APIM says, "Sorry, you can't go in!" and blocks them from accessing the API.

Difference Between Azure AD (Gatekeeper) and APIM (Security Guard):

• Azure AD (Gatekeeper):

  • Makes sure the right users or apps get the correct ID badge (JWT token).
  • Ensures the user is authenticated (verified identity).

• APIM (Security Guard):

  • Checks the ID badge (JWT) that Azure AD issued to ensure it’s valid and that the user has the right access.
  • Controls access to specific APIs and enforces rules about what the user or app can do.
  • Optionally performs additional security checks like rate limiting, throttling, or even transforming API requests to keep the APIs safe.

Why You Need Both:

• Azure AD makes sure that only trusted users get access to the system and provides them with an identity token (the ID badge).
• APIM ensures that these trusted users have appropriate permissions to access and interact with the APIs. It also protects the APIs from being overused or misused.

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Simplified Example:

Imagine you're trying to enter a secured building (the API) with a bouncer outside.

1. Azure AD (Gatekeeper): Before you even approach the building, you go to the gatekeeper and show your ID (username and password). If everything checks out, they hand you a special ID badge (JWT) that tells the bouncer who you are and what you're allowed to do.

2. APIM (Bouncer): You then walk up to the bouncer standing at the door of the building (API). The bouncer reads your ID badge (JWT) and makes sure:

   • The ID badge is real and valid.
   • The badge says you're allowed to enter the building and go to specific rooms (APIs).

   If everything checks out, the bouncer lets you in. If not, they stop you from entering.

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Conclusion:

• Azure AD: Provides authentication and verifies who the person is.
• APIM: Provides authorization and additional security by checking what the person is allowed to do and protecting the APIs from misuse.

So, in this analogy, APIM is the security guard (bouncer) that makes sure only the right people with valid permissions get access to the APIs after Azure AD (the gatekeeper) has verified their identity and issued them a valid JWT token (ID badge).