login-project-kotlin

A simple but robust user login system written in Kotlin. This console-based project supports username/password authentication, role-based access control, password hashing, and stores all data in a local JSON file.

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🔑 Features

• User login with username and password
• Hashed passwords
• Role-based access (admin and user)
• Logging user actions such as login, logout, and password changes
• Admin panel:
  • View all users
  • Add users
  • Remove users
  • Change users' passwords
• Prevents:
  • Duplicate usernames
  • Deleting the currently logged-in account
• Clean console interaction with basic input validation
• Readable and clean code structure

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🚀 Getting Started

1. Clone the repository.
2. Open in IntelliJ IDEA or another Kotlin-compatible IDE.
3. Make sure kotlinx.serialization is set up.
4. Make sure that file at data/users.json with this content:

[
  {
    "username": "admin",
    "password": "8c6976e5b5410415bde908bd4dee15dfb167a9c873fc4bb8a81f6f2ab448a918",
    "auth": "admin"
  }
]

5. Run the app. Use admin as both username and password to log in.

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📌 Notes

• User actions like login, logout, and password changes are now logged to logs/log.txt for audit and tracking purposes.
• Logs include timestamps and usernames for better traceability.
• All data is stored in a flat JSON file — no database required.