Secure credential storage hinges on password hashing: never store plaintext; hash with modern, slow, adaptive algorithms (bcrypt, PBKDF2, Argon2) and avoid MD5/SHA‑1; harden with per‑user salts, a secret pepper, and a tuned work factor; store salts separately and update algorithms over time; example flow shows signup/login with bcrypt+salt+pepper to defeat brute‑force and breaches.