User Auth From Scratch in C

This video demonstrates implementing secure client authentication for an instant messenger using asymmetric cryptography (ED25519) with OpenSSL. The key concepts include generating public-private key pairs for each client, sending the public key during the handshake protocol, and using the server to verify client identity through cryptographic signatures. The implementation addresses a critical security vulnerability where client-generated IDs could be spoofed, and instead uses cryptographically secure key pairs to ensure only legitimate clients can authenticate. The video also covers practical challenges in C programming including memory management, buffer handling, and debugging network protocol implementations.