[Spring Boot] 61. 스프링부트 블로그 v3 (RestAPI) (6) SHA-256 기반 비밀번호 해싱 실습

package com.example.loginapp.user;

import com.example.loginapp._core.util.SHA256Util;
import org.mindrot.jbcrypt.BCrypt;
import com.example.loginapp._core.error.ex.Exception400;
import com.example.loginapp._core.error.ex.Exception401;
import com.example.loginapp._core.error.ex.Exception404;
import lombok.RequiredArgsConstructor;
import org.springframework.stereotype.Service;
import org.springframework.transaction.annotation.Transactional;

import java.util.HashMap;
import java.util.Map;

@RequiredArgsConstructor
@Service
// 책임 : 트랜잭션 처리, 비지니스 로직, DTO 완료
public class UserService {
    private final UserRepository userRepository;

    @Transactional
    public void join(UserRequest.JoinDTO joinDTO) {
        try {
            String encPassword = SHA256Util.encrypt(joinDTO.getPassword());
            joinDTO.setPassword(encPassword);

            userRepository.save(joinDTO.toEntity());
        } catch (Exception e) {
            throw new Exception400("이미 존재하는 아이디로 회원가입 하지 마세요. postman도 쓰지 마세요.");
        }
    }

    public User login(UserRequest.LoginDTO loginDTO) {
        // 1. username 일치 검사
        User user = userRepository.findByUsername(loginDTO.getUsername());
        // 2. username 불일치 -> Exception
        if (user == null) throw new Exception401("username 혹은 password가 틀렸습니다.");
        // 3. password 불일치 -> Exception
        String encPassword = SHA256Util.encrypt(loginDTO.getPassword());
        if (!encPassword.equals(user.getPassword())) {
            throw new Exception401("username 혹은 password가 틀렸습니다.");
        }
        // 4. username & password 전부 일치
        return user;
    }

    public Map<String, Object> 유저네임중복체크(String username) {
        User user = userRepository.findByUsername(username);
        Map<String, Object> dto = new HashMap<>();

        if (user == null) {
            dto.put("available", true);
        } else {
            dto.put("available", false);
        }
        return dto;
    }

    @Transactional
    public User 회원정보수정(UserRequest.UpdateDTO updateDTO, Integer id) {
        User user = userRepository.findById(id);
        if (user == null) throw new Exception404("회원을 찾을 수 없습니다.");
        user.update(updateDTO.getPassword(), updateDTO.getEmail());
        return user;
    }
}

package com.example.loginapp._core.util;

import java.nio.charset.StandardCharsets;
import java.security.MessageDigest;
import java.security.NoSuchAlgorithmException;

public class SHA256Util {
    public static String encrypt(String rawPassword) {
        try {
            MessageDigest digest = MessageDigest.getInstance("SHA-256");
            byte[] hash = digest.digest(rawPassword.getBytes(StandardCharsets.UTF_8));
            StringBuilder hexString = new StringBuilder();

            for (byte b : hash) {
                String hex = Integer.toHexString(0xff & b);
                if (hex.length() == 1) hexString.append('0');
                hexString.append(hex);
            }

            return hexString.toString();
        } catch (NoSuchAlgorithmException e) {
            throw new RuntimeException("SHA-256 해싱 오류 발생", e);
        }
    }
}

insert into user_tb(username, password, email, created_at)
values ('ssar', '03ac674216f3e15c761ee1a5e255f067953623c8b388b4459e13f978d7c846f4', 'ssar@nate.com', now());
insert into user_tb(username, password, email, created_at)
values ('cos', '03ac674216f3e15c761ee1a5e255f067953623c8b388b4459e13f978d7c846f4', 'cos@nate.com', now());
insert into user_tb(username, password, email, created_at)
values ('love', '03ac674216f3e15c761ee1a5e255f067953623c8b388b4459e13f978d7c846f4', 'love@nate.com', now());

insert into board_tb(title, content, user_id, created_at)
values ('제목1', '내용1', 1, now());
insert into board_tb(title, content, user_id,  created_at)
values ('제목2', '내용2', 1, now());
insert into board_tb(title, content, user_id, created_at)
values ('제목3', '내용3', 2, now());
insert into board_tb(title, content, user_id, created_at)
values ('제목4', '내용4', 3, now());
insert into board_tb(title, content, user_id, created_at)
values ('제목5', '내용5', 1, now());