Learn Rust Coding · Lesson

Authentication and Authorization

Implement secure user authentication (e.g., JWT) and authorization mechanisms to protect your web service endpoints.

Authentication and Authorization is a free Learn Rust Coding lesson on CoddyKit — lesson 3 of 3. You can read the complete lesson below for free — then practise it hands-on in the browser with a built-in code editor and a 24/7 AI tutor. It is part of the Learn Rust Coding learning path, one of 3 lessons in the course, and your progress syncs across the web and the CoddyKit app.

Secure Your Web Services

Welcome! In this lesson, we'll dive into Authentication and Authorization, crucial concepts for building secure web services in Rust.

You'll learn how to protect your API endpoints by ensuring only legitimate users can access them, and only with the right permissions.

Authentication vs. Authorization

These two terms sound similar but mean different things:

Authentication: Verifies who you are. It's like showing your ID to enter a building.
Authorization: Determines what you're allowed to do. Once inside, it's about which rooms you can enter.

We'll implement both to secure our Rust web services.

Why Secure Your APIs?

Protecting your API endpoints is vital for several reasons:

Data Privacy: Keep sensitive user data safe from unauthorized access.
System Integrity: Prevent malicious actors from altering or corrupting your data.
Compliance: Meet legal and regulatory requirements (e.g., GDPR, HIPAA).

A robust security layer builds trust and protects your application.

JSON Web Tokens (JWTs)

A popular method for authentication in modern web services is using JSON Web Tokens (JWTs), pronounced "jot".

JWTs are compact, URL-safe means of representing claims to be transferred between two parties. They are often used for stateless authentication.

This means the server doesn't need to store session information for each user.

Inside a JWT: Header, Payload, Signature

A JWT consists of three parts, separated by dots:

Header: Contains metadata about the token, like the type of token (JWT) and the signing algorithm (e.g., HS256).
Payload: Contains the "claims" – statements about an entity (usually the user) and additional data.
Signature: Used to verify the token hasn't been tampered with. It's created by encoding the header and payload with a secret key.

Generating & Verifying JWTs in Rust

Let's see how to generate and verify a JWT using the jsonwebtoken crate in Rust. Remember, you'll need to add jsonwebtoken, serde (with "derive" feature), and chrono (with "serde" feature) to your Cargo.toml.

This example generates a token, then immediately verifies it.

use jsonwebtoken::{encode, decode, Header, EncodingKey, DecodingKey, Validation};
use serde::{Deserialize, Serialize};
use chrono::{Utc, Duration};

#[derive(Debug, Serialize, Deserialize)]
struct Claims {
    sub: String, // Subject (user ID)
    company: String,
    exp: usize,  // Expiration time
}

fn main() {
    // --- Setup (requires crates: jsonwebtoken, serde, chrono) ---
    let secret_key = "my_super_secret_key";

    // --- 1. Generate a JWT ---
    let my_claims = Claims {
        sub: "user123".to_string(),
        company: "CoddyKit".to_string(),
        exp: (Utc::now() + Duration::minutes(10)).timestamp() as usize,
    };
    let token = encode(
        &Header::default(),
        &my_claims,
        &EncodingKey::from_secret(secret_key.as_ref()),
    ).expect("Failed to encode token");
    println!("Generated JWT:\n{}", token);
    println!("\n--- Verifying the Token ---");

    // --- 2. Verify the JWT ---
    let validation = Validation::default();
    let decoded_result = decode::<Claims>(
        &token,
        &DecodingKey::from_secret(secret_key.as_ref()),
        &validation,
    );

    match decoded_result {
        Ok(token_data) => {
            println!("Token valid!");
            println!("Subject: {}", token_data.claims.sub);
            println!("Company: {}", token_data.claims.company);
        },
        Err(err) => println!("Token invalid: {:?}", err),
    }
}

Authorization: Defining Access

Once a user is authenticated (we know who they are), authorization determines what resources or actions they are permitted to access.

Common authorization models include:

Role-Based Access Control (RBAC): Users are assigned roles (e.g., "admin", "editor", "viewer"), and roles have specific permissions.
Attribute-Based Access Control (ABAC): Access is granted based on attributes of the user, resource, or environment.

Authorization Middleware Concept

In a web service, authorization is often handled by middleware. This is code that runs before your main route handler.

The middleware would:

Extract the authenticated user's identity (e.g., from a JWT).
Check their roles or permissions against the required access for the requested endpoint.
If authorized, allow the request to proceed; otherwise, return an "Unauthorized" or "Forbidden" error.

This keeps your route handlers clean and focused on business logic.

Testing Your Knowledge

Let's quickly check your understanding of authentication and authorization.

Recap: Securing Web Services

Great job! In this lesson, we covered the essentials of securing your Rust web services:

The difference between Authentication (who you are) and Authorization (what you can do).
The importance of protecting API endpoints.
How JSON Web Tokens (JWTs) work for stateless authentication, including their structure.
A practical Rust example of generating and verifying JWTs.
Concepts of Role-Based Access Control and how middleware can implement authorization checks.

You're now ready to build more secure and robust Rust applications!

Frequently asked questions

Is the “Authentication and Authorization” lesson free?

Yes — the full text of “Authentication and Authorization” is free to read here on the web, and the Learn Rust Coding course includes 3 lessons in total. To practise it interactively (a built-in code editor and a 24/7 AI tutor) and unlock the rest of the Learn Rust Coding course, upgrade to CoddyKit PRO.

What will I learn in “Authentication and Authorization”?

Implement secure user authentication (e.g., JWT) and authorization mechanisms to protect your web service endpoints. You practise Learn Rust Coding with hands-on code you run directly in the browser, and a 24/7 AI tutor answers your questions as you work through the lesson.

Do I need any experience to start Learn Rust Coding?

No prior experience is required. Learn Rust Coding on CoddyKit is structured for beginners through advanced learners; this is — lesson 3 of 3, so you can start here or from the beginning and move at your own pace.

How long does the “Authentication and Authorization” lesson take?

Most CoddyKit lessons take about 5–10 minutes. Each one is bite-sized and interactive, so you make steady progress and pick up exactly where you left off across the web and the app.

Can I write and run code in this Learn Rust Coding lesson?

Yes. Every Learn Rust Coding lesson includes a built-in code editor, so you write and run real code right in your browser and get instant AI feedback — no local setup required.

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