Why Passwords Must Be Hashed Storing plaintext passwords is a critical security failure. When a database is breached, attackers immediately have every user’s password — and because people reuse passwords, those credentials work on other sites too. Password hashing is not encryption. Encryption is reversible. Hashing is one-way: you can verify a password by hashing it and comparing to the stored hash, but you cannot recover the original password from the hash.

Secure Registration Registration is where passwords enter your system. Get it wrong here and no amount of downstream security saves you. The Registration Flow User submits form → Validate password strength → Check username/email uniqueness → Encode password with PasswordEncoder → Persist user (disabled) → Send verification email → User clicks link → enable account Registration Endpoint @RestController @RequestMapping("/auth") public class RegistrationController { private final UserService userService; private final PasswordEncoder passwordEncoder; @PostMapping("/register") public ResponseEntity<Void> register(@Valid @RequestBody RegistrationRequest request) { userService.