PasswordHashService

Info

@Component providing BCrypt password hashing with backward-compatible SHA-256 verification for legacy accounts.

Overview

New passwords are hashed with BCrypt via Spring Security's PasswordEncoder. For backward compatibility, matches() also supports legacy SHA-256 hashes using constant-time comparison to prevent timing attacks. UserService automatically upgrades SHA-256 hashes to BCrypt on successful login.

Methods

Method	Return	Description
hash(rawPassword)	String	Generate BCrypt hash
matches(rawPassword, storedHash)	boolean	Verify password against BCrypt or SHA-256 hash
isBcrypt(storedHash)	boolean	Check if hash starts with $2a$, $2b$, or $2y$

Hash Format Detection

Prefix	Algorithm	Action
$2a$, $2b$, $2y$	BCrypt	Use PasswordEncoder.matches()
(other)	SHA-256 (legacy)	SHA-256 the input, then constant-time compare

Security Notes

• SHA-256 comparison uses constant-time XOR to prevent timing side-channel attacks
• Legacy SHA-256 hashes are automatically upgraded to BCrypt on successful authentication (handled by UserService.authenticateUser())
• The BCrypt PasswordEncoder is injected via Spring Security configuration

Dependencies

• PasswordEncoder (Spring Security) -- BCrypt encoding and matching