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Labs / JWT Algo Confusion

  • Daily Challenge
  • Released 28 Jul 2025
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Daily Challenge

JWT Algorithm Confusion - Challenge Description

Challenge Overview

Welcome to JWT Algorithm Confusion! In this challenge, you'll explore JWT token security and discover vulnerabilities in token validation mechanisms. The application implements JWT-based authentication with interesting security implications that you'll need to uncover.

Learning Objectives

  • Understand JWT structure and components (header, payload, signature)
  • Learn about different JWT signing algorithms and their security properties
  • Explore token validation processes and potential weaknesses
  • Practice JWT security analysis and token manipulation techniques

Challenge Details

The challenge presents a Flask authentication service that implements JWT-based security. You'll need to analyze the authentication system, understand how tokens are generated and validated, and find a way to gain administrative access to retrieve the flag.

Technical Background

JSON Web Tokens (JWT) are a popular method for securely transmitting information between parties. They consist of three parts: header, payload, and signature. Different algorithms can be used for signing tokens, each with their own security characteristics. Understanding these algorithms and their implementations is crucial for identifying potential security vulnerabilities.

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Mazer72