Spring Security와 JWT 통합하기: 단계별 가이드

Spring Security와 JWT 통합하기: 단계별 가이드

Spring Boot 애플리케이션에서 JWT(JSON Web Token)를 활용하여 인증과 권한 부여를 구현하면 보안성과 확장성을 높일 수 있습니다. 이 글에서는 Spring Security와 JWT를 통합하여 인증 시스템을 구축하는 방법을 단계별로 설명합니다.

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1. JWT란?

JWT(JSON Web Token)는 JSON 데이터를 기반으로 인증 정보를 안전하게 전송하기 위한 토큰 기반 인증 방식입니다.

구조:
JWT는 Header.Payload.Signature로 구성됩니다.

• Header: 토큰 유형과 해싱 알고리즘 정보를 포함
• Payload: 사용자 정보와 클레임(Claim)을 포함
• Signature: Header와 Payload를 서명하여 변조를 방지

예제 JWT:

eyJhbGciOiJIUzI1NiIsInR5cCI6IkpXVCJ9.eyJzdWIiOiJ1c2VyMSIsInJvbGVzIjpbIlJPTEVfVVNFUiJdLCJpYXQiOjE2NzMwMjc4ODAsImV4cCI6MTY3MzAyODI0MH0.abc123signature

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2. 프로젝트 설정

의존성 추가:
Spring Security와 JWT 관련 라이브러리를 추가합니다.

Maven:

<dependency>
    <groupId>org.springframework.boot</groupId>
    <artifactId>spring-boot-starter-security</artifactId>
</dependency>
<dependency>
    <groupId>io.jsonwebtoken</groupId>
    <artifactId>jjwt-api</artifactId>
    <version>0.11.5</version>
</dependency>
<dependency>
    <groupId>io.jsonwebtoken</groupId>
    <artifactId>jjwt-impl</artifactId>
    <version>0.11.5</version>
    <scope>runtime</scope>
</dependency>
<dependency>
    <groupId>io.jsonwebtoken</groupId>
    <artifactId>jjwt-jackson</artifactId>
    <version>0.11.5</version>
    <scope>runtime</scope>
</dependency>

Gradle:

dependencies {
    implementation 'org.springframework.boot:spring-boot-starter-security'
    implementation 'io.jsonwebtoken:jjwt-api:0.11.5'
    runtimeOnly 'io.jsonwebtoken:jjwt-impl:0.11.5'
    runtimeOnly 'io.jsonwebtoken:jjwt-jackson:0.11.5'
}

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3. JWT 유틸리티 클래스 생성

JWT 토큰을 생성하고 검증하는 유틸리티 클래스를 작성합니다.

JwtUtil.java:

import io.jsonwebtoken.Claims;
import io.jsonwebtoken.Jwts;
import io.jsonwebtoken.SignatureAlgorithm;
import org.springframework.stereotype.Component;

import java.util.Date;
import java.util.function.Function;

@Component
public class JwtUtil {

    private final String SECRET_KEY = "mysecretkey";

    public String extractUsername(String token) {
        return extractClaim(token, Claims::getSubject);
    }

    public Date extractExpiration(String token) {
        return extractClaim(token, Claims::getExpiration);
    }

    public <T> T extractClaim(String token, Function<Claims, T> claimsResolver) {
        final Claims claims = extractAllClaims(token);
        return claimsResolver.apply(claims);
    }

    private Claims extractAllClaims(String token) {
        return Jwts.parser().setSigningKey(SECRET_KEY).parseClaimsJws(token).getBody();
    }

    private Boolean isTokenExpired(String token) {
        return extractExpiration(token).before(new Date());
    }

    public String generateToken(String username) {
        return Jwts.builder()
                .setSubject(username)
                .setIssuedAt(new Date(System.currentTimeMillis()))
                .setExpiration(new Date(System.currentTimeMillis() + 1000 * 60 * 60 * 10))
                .signWith(SignatureAlgorithm.HS256, SECRET_KEY)
                .compact();
    }

    public Boolean validateToken(String token, String username) {
        final String extractedUsername = extractUsername(token);
        return (extractedUsername.equals(username) && !isTokenExpired(token));
    }
}

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4. Spring Security 구성

JWT를 활용하여 인증을 처리하도록 Spring Security 설정을 작성합니다.

SecurityConfig.java:

import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
import org.springframework.security.authentication.AuthenticationManager;
import org.springframework.security.config.annotation.authentication.configuration.AuthenticationConfiguration;
import org.springframework.security.config.annotation.web.builders.HttpSecurity;
import org.springframework.security.config.http.SessionCreationPolicy;
import org.springframework.security.crypto.bcrypt.BCryptPasswordEncoder;
import org.springframework.security.crypto.password.PasswordEncoder;
import org.springframework.security.web.SecurityFilterChain;

@Configuration
public class SecurityConfig {

    @Bean
    public SecurityFilterChain securityFilterChain(HttpSecurity http) throws Exception {
        http
            .csrf().disable()
            .authorizeRequests()
                .antMatchers("/api/auth/**").permitAll()
                .anyRequest().authenticated()
            .and()
            .sessionManagement().sessionCreationPolicy(SessionCreationPolicy.STATELESS);
        return http.build();
    }

    @Bean
    public PasswordEncoder passwordEncoder() {
        return new BCryptPasswordEncoder();
    }

    @Bean
    public AuthenticationManager authenticationManager(AuthenticationConfiguration config) throws Exception {
        return config.getAuthenticationManager();
    }
}

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5. 컨트롤러 작성

AuthController.java:

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.security.authentication.AuthenticationManager;
import org.springframework.security.authentication.UsernamePasswordAuthenticationToken;
import org.springframework.security.core.Authentication;
import org.springframework.web.bind.annotation.*;

@RestController
@RequestMapping("/api/auth")
public class AuthController {

    @Autowired
    private JwtUtil jwtUtil;

    @Autowired
    private AuthenticationManager authenticationManager;

    @PostMapping("/login")
    public String login(@RequestBody AuthRequest authRequest) {
        Authentication authentication = authenticationManager.authenticate(
            new UsernamePasswordAuthenticationToken(authRequest.getUsername(), authRequest.getPassword())
        );
        return jwtUtil.generateToken(authRequest.getUsername());
    }
}

class AuthRequest {
    private String username;
    private String password;

    // Getter와 Setter
}

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6. JWT 필터 작성

Spring Security 필터 체인에서 JWT 토큰을 검증하는 필터를 추가합니다.

JwtFilter.java:

import org.springframework.stereotype.Component;
import javax.servlet.FilterChain;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import org.springframework.web.filter.OncePerRequestFilter;

@Component
public class JwtFilter extends OncePerRequestFilter {

    @Override
    protected void doFilterInternal(HttpServletRequest request, HttpServletResponse response, FilterChain chain)
            throws ServletException, java.io.IOException {
        // JWT 토큰 검증 로직 추가
        chain.doFilter(request, response);
    }
}

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7. 테스트 및 실행

1. 로그인 요청:

   • URL: POST /api/auth/login
   • Body:

     {
         "username": "user",
         "password": "password"
     }

   • Response: JWT 토큰

2. 보호된 엔드포인트 요청:

   • URL: GET /api/protected
   • Header: Authorization: Bearer <JWT>

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