Authentication From First Principles | SSH keys | JWT Token | Session ID | Authenticator App

Most developers think Session, JWT, SSH Keys, OTP, and Authenticator Apps are all competing authentication methods. They're wrong. These 5 systems don't even solve the same problem. In this video, I break down authentication from first principles — the way it was actually designed — so you finally understand what's really happening when you log into any app. We start with the only question that matters: how does a server prove who you are? From that single question, everything else falls into place. You'll understand why OTP, Authenticator Apps, and SSH Keys are fundamentally different from Sessions and JWT. You'll see how TOTP generates the same 6-digit code on your phone and the server without ever talking to each other. You'll understand why JWT can't be invalidated and what Refresh Tokens actually are — and why they're secretly just sessions in disguise. By the end of this video, you won't just know how authentication works. You'll know why it was built this way. Authentication Factors, Session Based Authentication, JWT, Refresh Tokens, OTP, TOTP, SSH Keys, HttpOnly Cookies, XSS Attacks, Multi Factor Authentication, Stateless vs Stateful Auth *Tags:* authentication, jwt tutorial, session vs token, ssh keys explained, how otp works, totp explained, refresh token, httponly cookie, web security, system design, backend development Enroll in Our Premium Courses: DSA: https://strikes.in/course/combo Web Dev: https://coderarmy.in/#home AI: https://strikes.in/course/689ee05f1d8... HLD Course: https://rohittnegi.akamai.net.in/new-... You can visit crypto website which I vibe coded: https://cryptography-learner.vercel.a...