implementing-jwt-signing-and-verification

# Implementing JWT Signing and Verification ## Overview JSON Web Tokens (JWT) defined in RFC 7519 are compact, URL-safe tokens used for authentication and authorization in web applications. This skill covers implementing secure JWT signing with HMAC-SHA256, RSA-PSS, and EdDSA algorithms, along with verification, token expiration, claims validation, and defense against common JWT attacks (algorithm confusion, none algorithm, key injection). ## When to Use - When deploying or configuring implementing jwt signing and verification capabilities in your environment - When establishing security controls aligned to compliance requirements - When building or improving security architecture for this domain - When conducting security assessments that require this implementation ## Prerequisites - Familiarity with cryptography concepts and tools - Access to a test or lab environment for safe execution - Python 3.8+ with required dependencies installed - Appropriate authorization for any testing activities ## Objectives - Implement JWT signing with HS256, RS256, ES256, and EdDSA - Verify JWT signatures and validate standard claims - Implement token expiration, not-before, and audience validation - Defend against algorithm confusion and none algorithm attacks - Implement JWT key rotation with JWK Sets - Build a complete authentication middleware ## Key Concepts ### JWT Algorithms | Algorithm | Type | Key | Security Level | |-----------|------|-----|---------------| | HS256 | Sy...