https://github.com/hendisantika/kotlin-spring-boot-3-spring-security-jwt

Spring Boot 3 (Spring Security 6) with Kotlin & JWT
https://github.com/hendisantika/kotlin-spring-boot-3-spring-security-jwt

Last synced: about 2 months ago
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Spring Boot 3 (Spring Security 6) with Kotlin & JWT

• Host: GitHub
• URL: https://github.com/hendisantika/kotlin-spring-boot-3-spring-security-jwt
• Owner: hendisantika
• Created: 2023-10-31T05:19:36.000Z (over 1 year ago)
• Default Branch: main
• Last Pushed: 2025-03-31T10:46:22.000Z (2 months ago)
• Last Synced: 2025-04-13T00:11:49.193Z (about 2 months ago)
• Language: Kotlin
• Size: 191 KB
• Stars: 5
• Watchers: 2
• Forks: 3
• Open Issues: 0
• Metadata Files:
  • Readme: README.md

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README

        
# kotlin-spring-boot-3-spring-security-jwt

Well, in our project we will implement a REST API for articles and users.

Articles will be visible to any user who successfully authenticates using the JWT access token.

Users endpoint, on the other hand, will be accessible only for admin users in our system (with one exception- a public

endpoint for creating new users).

Of course, we will expose additional authentication endpoints, which will take data from users, like email and password

and generate access and refresh tokens for our system.

Long story short- I believe this project will be simple enough to easily understand the topic, and comprehensive enough

to cover the most popular real-life cases.

### A Tiny Bit Of Theory

In this paragraph, I’d like to cover what exactly JWT tokens are, the difference between authorization and

authentication, and present from a bird’s eye view how Spring Security works.

So, if you feel that you understand these and came here for the practice, then please skip to the next chapter 😉

### Authentication vs Authorization

I am pretty sure that you heard both terms plenty of times already and even heard people using them alternately.

Nevertheless, although similar, these two terms refer to completely different things.

Imagine you’re at the entrance of a super-secret club:

**Authentication** is like showing your ID to prove you are who you say you are. It’s the process of confirming your

identity. So, in our club scenario, it’s like showing your driver’s license to the bouncer.

**Authorization**, on the other hand, is like being allowed into different parts of the club based on your VIP status.

Once you’re inside (thanks to authentication), authorization decides what you can and cannot do. For example, VIP

members might access the VIP lounge, while regular guests can’t.

### JWT Tokens

Among plenty of existing ways to authenticate users, JWTs (JSON Web Tokens) are one of the most popular ones.

They are like a digital secret handshake on the internet. When we log into a website, the server gives us a special JWT.

This token is like a digital badge that says, “Hey, this person is legit!”

Why are they so cool? Well, they are safe, compact, and allow us to hold information.

JWTs consist of three parts separated by dots: header.payload.signature:

**Spring Security** is like the security team of a building. It manages authentication and authorization for our app

with:

1. **Filters**– think of security filters as checkpoints at different doors in the building. When a request comes in, it

   goes through these filters. These filters handle tasks like authentication and authorization. For instance, there

   might be a filter that checks if you have a proper access card (authentication), and another that ensures you can

   enter specific rooms (authorization).

2. **Authentication**– when you log in, Spring Security checks your credentials (like username and password). If they

   match, you’re authenticated. Spring Security uses authentication providers, which can be a database, LDAP, or any

   other source, to verify your identity.

3. **Security Context**– once authenticated, your security details are stored in the Security Context. It’s like being

   given a special pass after passing through the checkpoint. This pass (security context) contains your roles and

   permissions.

4. **Authorization**– now, when you try to access a specific part of the application, Spring Security checks your roles

   and permissions stored in the security context. If you’re authorized (based on your roles), you’re allowed in.

   Otherwise, you might be denied access.

5. **Customization**– Spring Security allows you to customize the security filters, authentication providers, and access

   rules according to your application’s requirements. You can configure which URLs need authentication, what roles are

   required, etc.