test(ap1): demonstrate token storage tradeoff

.gitignore

@@ -4,4 +4,6 @@
 *.iml
 
 backend/target/
+**/node_modules/
+frontend/dist/
 build/

README.md

@@ -96,3 +96,34 @@ Keycloak을 잠시 중지하고 export한 뒤 자동으로 다시 올립니다.
 
 runtime export에는 실제 client secret과 credential hash가 포함될 수 있어
 gitignored `build/keycloak-export/`에 권한 `0600`으로만 저장됩니다.
+
+## AP1: SPA Direct + Resource Server
+
+`develop-keycloak-pattern1`은 vanilla JavaScript SPA가 `spa-public` client로
+Authorization Code + PKCE S256 로그인을 수행하는 패턴입니다. access/refresh
+token은 명시적인 in-memory store에만 보관되므로 새로고침하면 사라집니다.
+
+```bash
+./scripts/verify-pattern1.sh
+```
+
+브라우저에서 `http://localhost:8088`을 열어 로그인한 뒤 보호 API를 호출할 수
+있습니다. SPA는 `http://localhost:8081/api/me`를 직접 호출하며 Spring
+Resource Server가 Bearer JWT를 검증합니다.
+
+Keycloak의 dedicated audience mapper는 `spa-public` access token에
+`keycloak-pattern-api`를 추가합니다. Spring은 signature, `iss`, `exp`뿐
+아니라 이 `aud`도 검사합니다. `verify-pattern1.sh`는 같은 정상 토큰을
+`deliberately-wrong-audience`를 기대하는 진단 인스턴스에도 제출해 `401`을
+확인합니다.
+
+Keycloak은 `KC_HOSTNAME=http://localhost:8080`을 기준으로 token의 `iss`를
+발급합니다. 정상 Resource Server는 이 외부 issuer 문자열을 검증하되 JWKS는
+Docker 내부의 `http://keycloak:8080`에서 가져옵니다. 진단 인스턴스는 일부러
+`http://wrong-issuer.invalid`를 기대하도록 구성되어, 서명과 audience가
+정상이더라도 issuer mismatch로 `401`을 반환합니다.
+
+token 저장 위치와 XSS 범위는
+[`docs/ap1-token-storage.md`](docs/ap1-token-storage.md)에 정리했습니다.
+E2E는 Web Storage token이 0개임과 동시에 실행 중 fetch hook이 Bearer
+header를 관찰할 수 있음을 재현합니다.

backend/src/main/java/com/example/keycloakpattern/AudienceValidator.java

@@ -0,0 +1,29 @@
+package com.example.keycloakpattern;
+
+import org.springframework.security.oauth2.core.OAuth2Error;
+import org.springframework.security.oauth2.core.OAuth2TokenValidator;
+import org.springframework.security.oauth2.core.OAuth2TokenValidatorResult;
+import org.springframework.security.oauth2.jwt.Jwt;
+
+final class AudienceValidator implements OAuth2TokenValidator<Jwt> {
+
+    private static final OAuth2Error MISSING_AUDIENCE = new OAuth2Error(
+        "invalid_token",
+        "The required resource audience is missing",
+        null
+    );
+
+    private final String expectedAudience;
+
+    AudienceValidator(String expectedAudience) {
+        this.expectedAudience = expectedAudience;
+    }
+
+    @Override
+    public OAuth2TokenValidatorResult validate(Jwt jwt) {
+        if (jwt.getAudience().contains(expectedAudience)) {
+            return OAuth2TokenValidatorResult.success();
+        }
+        return OAuth2TokenValidatorResult.failure(MISSING_AUDIENCE);
+    }
+}

backend/src/main/java/com/example/keycloakpattern/JwtDecoderConfig.java

@@ -0,0 +1,31 @@
+package com.example.keycloakpattern;
+
+import org.springframework.beans.factory.annotation.Value;
+import org.springframework.context.annotation.Bean;
+import org.springframework.context.annotation.Configuration;
+import org.springframework.security.oauth2.core.DelegatingOAuth2TokenValidator;
+import org.springframework.security.oauth2.core.OAuth2TokenValidator;
+import org.springframework.security.oauth2.jwt.Jwt;
+import org.springframework.security.oauth2.jwt.JwtDecoder;
+import org.springframework.security.oauth2.jwt.JwtValidators;
+import org.springframework.security.oauth2.jwt.NimbusJwtDecoder;
+
+@Configuration
+public class JwtDecoderConfig {
+
+    @Bean
+    JwtDecoder jwtDecoder(
+        @Value("${spring.security.oauth2.resourceserver.jwt.issuer-uri}") String issuer,
+        @Value("${spring.security.oauth2.resourceserver.jwt.jwk-set-uri}") String jwkSetUri,
+        @Value("${security.expected-audience}") String expectedAudience
+    ) {
+        NimbusJwtDecoder decoder = NimbusJwtDecoder.withJwkSetUri(jwkSetUri).build();
+        OAuth2TokenValidator<Jwt> issuerAndTimestamp =
+            JwtValidators.createDefaultWithIssuer(issuer);
+        OAuth2TokenValidator<Jwt> audience = new AudienceValidator(expectedAudience);
+        decoder.setJwtValidator(
+            new DelegatingOAuth2TokenValidator<>(issuerAndTimestamp, audience)
+        );
+        return decoder;
+    }
+}

backend/src/main/java/com/example/keycloakpattern/SecurityConfig.java

@@ -1,11 +1,16 @@
 package com.example.keycloakpattern;
 
+import java.util.List;
+
 import org.springframework.context.annotation.Bean;
 import org.springframework.context.annotation.Configuration;
 import org.springframework.security.config.Customizer;
 import org.springframework.security.config.annotation.web.builders.HttpSecurity;
 import org.springframework.security.config.http.SessionCreationPolicy;
 import org.springframework.security.web.SecurityFilterChain;
+import org.springframework.web.cors.CorsConfiguration;
+import org.springframework.web.cors.CorsConfigurationSource;
+import org.springframework.web.cors.UrlBasedCorsConfigurationSource;
 
 @Configuration
 public class SecurityConfig {
@@ -13,6 +18,7 @@ public class SecurityConfig {
     @Bean
     SecurityFilterChain apiSecurity(HttpSecurity http) throws Exception {
         return http
+            .cors(Customizer.withDefaults())
             .csrf(csrf -> csrf.disable())
             .sessionManagement(session ->
                 session.sessionCreationPolicy(SessionCreationPolicy.STATELESS))
@@ -24,4 +30,19 @@ public class SecurityConfig {
             .oauth2ResourceServer(oauth2 -> oauth2.jwt(Customizer.withDefaults()))
             .build();
     }
+
+    @Bean
+    CorsConfigurationSource corsConfigurationSource() {
+        CorsConfiguration configuration = new CorsConfiguration();
+        configuration.setAllowedOrigins(List.of(
+            "http://localhost:8088",
+            "http://127.0.0.1:8088"
+        ));
+        configuration.setAllowedMethods(List.of("GET", "OPTIONS"));
+        configuration.setAllowedHeaders(List.of("Authorization", "Content-Type"));
+
+        UrlBasedCorsConfigurationSource source = new UrlBasedCorsConfigurationSource();
+        source.registerCorsConfiguration("/api/**", configuration);
+        return source;
+    }
 }

backend/src/main/resources/application.yml

@@ -11,6 +11,9 @@ spring:
           issuer-uri: ${SPRING_SECURITY_OAUTH2_RESOURCESERVER_JWT_ISSUER_URI:http://localhost:8080/realms/keycloak-patterns}
           jwk-set-uri: ${SPRING_SECURITY_OAUTH2_RESOURCESERVER_JWT_JWK_SET_URI:http://localhost:8080/realms/keycloak-patterns/protocol/openid-connect/certs}
 
+security:
+  expected-audience: ${SECURITY_EXPECTED_AUDIENCE:keycloak-pattern-api}
+
 management:
   endpoint:
     health:

backend/src/test/java/com/example/keycloakpattern/AudienceValidatorTest.java

@@ -0,0 +1,49 @@
+package com.example.keycloakpattern;
+
+import static org.assertj.core.api.Assertions.assertThat;
+
+import java.time.Instant;
+import java.util.List;
+import java.util.Map;
+
+import org.junit.jupiter.api.Test;
+import org.springframework.security.oauth2.core.OAuth2TokenValidatorResult;
+import org.springframework.security.oauth2.jwt.Jwt;
+
+class AudienceValidatorTest {
+
+    private final AudienceValidator validator =
+        new AudienceValidator("keycloak-pattern-api");
+
+    @Test
+    void acceptsRequiredAudience() {
+        OAuth2TokenValidatorResult result = validator.validate(jwtWithAudience(
+            List.of("account", "keycloak-pattern-api")
+        ));
+
+        assertThat(result.hasErrors()).isFalse();
+    }
+
+    @Test
+    void rejectsForeignAudience() {
+        OAuth2TokenValidatorResult result = validator.validate(jwtWithAudience(
+            List.of("another-resource")
+        ));
+
+        assertThat(result.hasErrors()).isTrue();
+        assertThat(result.getErrors())
+            .extracting(error -> error.getErrorCode())
+            .containsExactly("invalid_token");
+    }
+
+    private Jwt jwtWithAudience(List<String> audience) {
+        Instant now = Instant.now();
+        return new Jwt(
+            "test-token",
+            now,
+            now.plusSeconds(300),
+            Map.of("alg", "none"),
+            Map.of("sub", "test-subject", "aud", audience)
+        );
+    }
+}

docker-compose.yml

@@ -86,6 +86,58 @@ services:
       - keycloak-net
     restart: unless-stopped
 
+  app-wrong-audience:
+    profiles:
+      - diagnostics
+    build:
+      context: ./backend
+    environment:
+      SERVER_PORT: "8081"
+      SPRING_SECURITY_OAUTH2_RESOURCESERVER_JWT_ISSUER_URI: http://localhost:8080/realms/keycloak-patterns
+      SPRING_SECURITY_OAUTH2_RESOURCESERVER_JWT_JWK_SET_URI: http://keycloak:8080/realms/keycloak-patterns/protocol/openid-connect/certs
+      SECURITY_EXPECTED_AUDIENCE: deliberately-wrong-audience
+    ports:
+      - "127.0.0.1:18081:8081"
+    depends_on:
+      keycloak:
+        condition: service_healthy
+    healthcheck:
+      test:
+        - CMD-SHELL
+        - wget -q -O - http://127.0.0.1:8081/actuator/health | grep -q '"status":"UP"'
+      interval: 10s
+      timeout: 5s
+      retries: 12
+      start_period: 20s
+    networks:
+      - keycloak-net
+
+  app-wrong-issuer:
+    profiles:
+      - diagnostics
+    build:
+      context: ./backend
+    environment:
+      SERVER_PORT: "8081"
+      SPRING_SECURITY_OAUTH2_RESOURCESERVER_JWT_ISSUER_URI: http://wrong-issuer.invalid/realms/keycloak-patterns
+      SPRING_SECURITY_OAUTH2_RESOURCESERVER_JWT_JWK_SET_URI: http://keycloak:8080/realms/keycloak-patterns/protocol/openid-connect/certs
+      SECURITY_EXPECTED_AUDIENCE: keycloak-pattern-api
+    ports:
+      - "127.0.0.1:18082:8081"
+    depends_on:
+      keycloak:
+        condition: service_healthy
+    healthcheck:
+      test:
+        - CMD-SHELL
+        - wget -q -O - http://127.0.0.1:8081/actuator/health | grep -q '"status":"UP"'
+      interval: 10s
+      timeout: 5s
+      retries: 12
+      start_period: 20s
+    networks:
+      - keycloak-net
+
   nginx:
     build:
       context: ./frontend

docs/ap1-token-storage.md

@@ -0,0 +1,29 @@
+# AP1 token storage trade-off
+
+AP1에서는 `access_token`, `refresh_token`, `id_token`을
+`oidc-client-ts`의 명시적인 `InMemoryWebStorage`에만 보관한다.
+`localStorage`와 `sessionStorage`에는 OAuth token을 저장하지 않는다.
+
+full-page authorization redirect를 생존해야 하는 일회성 transaction
+state와 PKCE verifier만 `sessionStorage`를 사용한다. callback 성공 후
+라이브러리가 해당 transaction state를 제거한다.
+
+| 저장 위치 | reload 생존 | JavaScript 접근 | AP1 선택 |
+|---|---:|---:|---:|
+| 메모리 | 아니요 | 실행 중 가능 | 사용 |
+| `sessionStorage` | 같은 탭에서 가능 | 가능 | token 저장 금지 |
+| `localStorage` | 예 | 가능 | token 저장 금지 |
+| HttpOnly cookie | 가능 | raw token 접근 불가 | AP2/AP3의 서버 소유 경계 |
+
+메모리 저장은 XSS를 제거하지 않는다. 악성 스크립트가 실행 중 `fetch`를
+후킹하면 SPA가 붙이는 `Authorization: Bearer ...` 헤더를 관찰할 수 있다.
+다만 persistent storage를 사용하지 않으므로 reload 이후 탈취 가능한 token
+복사본이 남지 않는다.
+
+`e2e/pattern1.mjs`는 다음 두 조건을 동시에 검증한다.
+
+1. access token이 Web Storage 어디에도 존재하지 않는다.
+2. 실행 중 fetch hook은 Bearer token을 관찰할 수 있다.
+
+따라서 결론은 “메모리면 XSS에 안전”이 아니라 “영속 탈취 범위를 줄이지만
+실행 중 XSS에는 여전히 노출”이다.

e2e/package-lock.json

@@ -0,0 +1,28 @@
+{
+  "name": "keycloak-pattern-e2e",
+  "version": "1.0.0",
+  "lockfileVersion": 3,
+  "requires": true,
+  "packages": {
+    "": {
+      "name": "keycloak-pattern-e2e",
+      "version": "1.0.0",
+      "devDependencies": {
+        "playwright-core": "1.62.0"
+      }
+    },
+    "node_modules/playwright-core": {
+      "version": "1.62.0",
+      "resolved": "https://registry.npmjs.org/playwright-core/-/playwright-core-1.62.0.tgz",
+      "integrity": "sha512-nsNRyq0r2zsG8AcRHWknc9QRA5XCueC7gWMrs+Gx2tlZn9hcl8zudfh00lhJPY1DE7NmZ6bDsT9g2yey8mXljA==",
+      "dev": true,
+      "license": "Apache-2.0",
+      "bin": {
+        "playwright-core": "cli.js"
+      },
+      "engines": {
+        "node": ">=20"
+      }
+    }
+  }
+}

e2e/package.json

@@ -0,0 +1,12 @@
+{
+  "name": "keycloak-pattern-e2e",
+  "private": true,
+  "version": "1.0.0",
+  "type": "module",
+  "scripts": {
+    "test:pattern1": "node pattern1.mjs"
+  },
+  "devDependencies": {
+    "playwright-core": "1.62.0"
+  }
+}

e2e/pattern1.mjs

@@ -0,0 +1,129 @@
+import assert from "node:assert/strict";
+import { chromium } from "playwright-core";
+
+const username = process.env.E2E_USERNAME ?? "regular-user";
+const password = process.env.E2E_PASSWORD;
+
+assert.ok(password, "E2E_PASSWORD must be set");
+
+const browser = await chromium.launch({
+  executablePath: process.env.CHROME_BIN ?? "/usr/bin/google-chrome",
+  headless: true,
+  args: ["--no-sandbox"],
+});
+
+try {
+  const context = await browser.newContext();
+  const page = await context.newPage();
+  let authorizationUrl;
+
+  page.on("request", (request) => {
+    if (request.url().includes("/protocol/openid-connect/auth")) {
+      authorizationUrl = new URL(request.url());
+    }
+  });
+
+  await page.goto("http://localhost:8088");
+  await page.locator("#login").click();
+  await page.waitForURL(/localhost:8080/u);
+  await page.locator("#username").fill(username);
+  await page.locator("#password").fill(password);
+  await page.locator("#kc-login").click();
+  await page.waitForURL("http://localhost:8088/");
+  await page.locator('[data-authenticated="true"]').waitFor();
+
+  assert.equal(authorizationUrl?.searchParams.get("response_type"), "code");
+  assert.equal(authorizationUrl?.searchParams.get("code_challenge_method"), "S256");
+  assert.ok(authorizationUrl?.searchParams.get("code_challenge"));
+
+  await page.evaluate(() => {
+    const originalFetch = window.fetch.bind(window);
+    window.__xssProbe = { authorization: null };
+    window.fetch = (input, init = {}) => {
+      const headers = new Headers(
+        init.headers ?? (input instanceof Request ? input.headers : undefined),
+      );
+      const authorization = headers.get("Authorization");
+      if (authorization) {
+        window.__xssProbe.authorization = authorization;
+      }
+      return originalFetch(input, init);
+    };
+  });
+
+  await page.locator("#call-api").click();
+  await page.waitForFunction(() => {
+    const text = document.querySelector("#result")?.textContent ?? "";
+    return text.includes('"httpStatus": 200');
+  });
+
+  const capturedAuthorization = await page.evaluate(
+    () => window.__xssProbe.authorization,
+  );
+  assert.match(capturedAuthorization, /^Bearer /u);
+  const accessToken = capturedAuthorization.slice("Bearer ".length);
+  const payload = JSON.parse(
+    Buffer.from(accessToken.split(".")[1], "base64url").toString("utf8"),
+  );
+  const audiences = Array.isArray(payload.aud) ? payload.aud : [payload.aud];
+  assert.ok(
+    audiences.includes("keycloak-pattern-api"),
+    "access token must target keycloak-pattern-api",
+  );
+
+  const storageSnapshot = await page.evaluate(() => ({
+    localStorage: Object.values(localStorage),
+    sessionStorage: Object.values(sessionStorage),
+  }));
+  assert.equal(
+    JSON.stringify(storageSnapshot).includes(accessToken),
+    false,
+    "access token must not be persisted in Web Storage",
+  );
+  assert.ok(
+    capturedAuthorization,
+    "runtime XSS-style fetch hooking can still observe a memory-only bearer token",
+  );
+
+  if (process.env.WRONG_AUDIENCE_URL) {
+    const response = await fetch(process.env.WRONG_AUDIENCE_URL, {
+      headers: { Authorization: `Bearer ${accessToken}` },
+    });
+    assert.equal(
+      response.status,
+      401,
+      "the same signed token must fail when the Resource Server expects another audience",
+    );
+  }
+
+  if (process.env.WRONG_ISSUER_URL) {
+    const response = await fetch(process.env.WRONG_ISSUER_URL, {
+      headers: { Authorization: `Bearer ${accessToken}` },
+    });
+    assert.equal(
+      response.status,
+      401,
+      "the same signed token must fail when the Resource Server expects another issuer",
+    );
+  }
+
+  await page.reload();
+  await page.locator('[data-authenticated="false"]').waitFor();
+  assert.equal(
+    await page.evaluate(
+      (token) => JSON.stringify({
+        localStorage: Object.values(localStorage),
+        sessionStorage: Object.values(sessionStorage),
+      }).includes(token),
+      accessToken,
+    ),
+    false,
+    "reload must clear the memory-only token without persisting it",
+  );
+
+  console.log(
+    "pattern1 browser verified: PKCE, audience/issuer negatives, persistent token 0, runtime fetch hook observes bearer, reload clears token",
+  );
+} finally {
+  await browser.close();
+}

frontend/Dockerfile

@@ -1,4 +1,16 @@
+FROM node:24-alpine AS build
+
+WORKDIR /workspace
+
+COPY package.json package-lock.json ./
+RUN npm ci
+
+COPY src ./src
+COPY test ./test
+RUN npm test && npm run build
+
 FROM nginx:1.29-alpine
 
 COPY nginx.conf /etc/nginx/conf.d/default.conf
 COPY index.html /usr/share/nginx/html/index.html
+COPY --from=build /workspace/dist/app.js /usr/share/nginx/html/app.js

frontend/index.html

@@ -3,31 +3,66 @@
 <head>
   <meta charset="utf-8">
   <meta name="viewport" content="width=device-width, initial-scale=1">
-  <title>Keycloak Authentication Patterns</title>
+  <meta name="referrer" content="no-referrer">
+  <title>AP1 · SPA Direct + Resource Server</title>
   <style>
     :root {
       color-scheme: light dark;
       font-family: system-ui, sans-serif;
     }
     body {
-      max-width: 48rem;
-      margin: 8vh auto;
+      max-width: 56rem;
+      margin: 6vh auto;
       padding: 0 1.5rem;
-      line-height: 1.6;
+      line-height: 1.55;
+    }
+    button {
+      margin: 0 0.5rem 0.5rem 0;
+      padding: 0.6rem 0.9rem;
+      cursor: pointer;
+    }
+    code, pre {
+      border-radius: 0.35rem;
+      background: color-mix(in srgb, CanvasText 9%, Canvas);
     }
     code {
-      padding: 0.15rem 0.35rem;
-      border-radius: 0.25rem;
-      background: color-mix(in srgb, CanvasText 10%, Canvas);
+      padding: 0.1rem 0.3rem;
+    }
+    pre {
+      min-height: 8rem;
+      padding: 1rem;
+      overflow: auto;
+      white-space: pre-wrap;
+    }
+    .notice {
+      border-left: 0.3rem solid #e09f3e;
+      padding-left: 1rem;
     }
   </style>
 </head>
 <body>
-  <h1>Keycloak Authentication Patterns</h1>
-  <p>공통 Docker Compose baseline이 실행 중입니다.</p>
-  <p>
-    공개 API는 <code>/api/public</code>, 보호 API는
-    <code>/api/me</code>에서 확인할 수 있습니다.
-  </p>
+  <main>
+    <h1>AP1 · SPA Direct + Resource Server</h1>
+    <p>
+      바닐라 JavaScript SPA가 <code>spa-public</code> client로 Authorization
+      Code + PKCE를 수행하고, access token을 직접 Spring Resource Server에
+      전달합니다.
+    </p>
+    <p class="notice">
+      access/refresh token은 메모리에만 존재합니다. 새로고침하면 사라지는 것이
+      이 패턴의 의도된 보안 경계입니다.
+    </p>
+
+    <section>
+      <button id="login" type="button">Keycloak 로그인</button>
+      <button id="call-api" type="button" disabled>보호 API 호출</button>
+      <button id="pkce-demo" type="button">수동 PKCE 생성</button>
+      <button id="logout" type="button" disabled>로그아웃</button>
+    </section>
+
+    <p id="session-state" data-authenticated="false">세션 확인 중…</p>
+    <pre id="result" aria-live="polite"></pre>
+  </main>
+  <script type="module" src="/app.js"></script>
 </body>
 </html>

frontend/nginx.conf

@@ -21,6 +21,7 @@ server {
     }
 
     location / {
+        add_header Cache-Control "no-store";
         try_files $uri $uri/ /index.html;
     }
 }

frontend/package-lock.json

@@ -0,0 +1,523 @@
+{
+  "name": "keycloak-pattern1-spa",
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+}

frontend/package.json

@@ -0,0 +1,16 @@
+{
+  "name": "keycloak-pattern1-spa",
+  "private": true,
+  "version": "1.0.0",
+  "type": "module",
+  "scripts": {
+    "build": "esbuild src/app.js --bundle --format=esm --outfile=dist/app.js --minify --sourcemap",
+    "test": "node --test test/*.test.mjs"
+  },
+  "dependencies": {
+    "oidc-client-ts": "3.5.0"
+  },
+  "devDependencies": {
+    "esbuild": "0.28.1"
+  }
+}

frontend/src/app.js

@@ -0,0 +1,131 @@
+import {
+  InMemoryWebStorage,
+  UserManager,
+  WebStorageStateStore,
+} from "oidc-client-ts";
+
+import { createPkcePair } from "./pkce.js";
+
+const authority = "http://localhost:8080/realms/keycloak-patterns";
+const backendBaseUrl = "http://localhost:8081";
+
+const userManager = new UserManager({
+  authority,
+  client_id: "spa-public",
+  redirect_uri: "http://localhost:8088/callback.html",
+  post_logout_redirect_uri: "http://localhost:8088/",
+  response_type: "code",
+  scope: "openid profile email",
+  automaticSilentRenew: true,
+  monitorSession: false,
+  loadUserInfo: false,
+  userStore: new WebStorageStateStore({
+    store: new InMemoryWebStorage(),
+  }),
+  stateStore: new WebStorageStateStore({
+    store: window.sessionStorage,
+  }),
+});
+
+const loginButton = document.querySelector("#login");
+const logoutButton = document.querySelector("#logout");
+const apiButton = document.querySelector("#call-api");
+const pkceButton = document.querySelector("#pkce-demo");
+const sessionState = document.querySelector("#session-state");
+const result = document.querySelector("#result");
+
+let currentUser = null;
+
+function renderJson(value) {
+  result.textContent = JSON.stringify(value, null, 2);
+}
+
+function tokenMetadata(user) {
+  return {
+    subject: user.profile.sub,
+    username: user.profile.preferred_username,
+    expiresAt: new Date(user.expires_at * 1000).toISOString(),
+    accessTokenHeldBy: "browser memory",
+    refreshTokenHeldBy: user.refresh_token ? "browser memory" : "not issued",
+  };
+}
+
+function renderSession(user) {
+  currentUser = user;
+  const authenticated = Boolean(user && !user.expired);
+  sessionState.dataset.authenticated = String(authenticated);
+  sessionState.textContent = authenticated
+    ? `${user.profile.preferred_username} 로그인됨 · token은 메모리에만 보관`
+    : "로그인되지 않음 · 브라우저 저장소에 token 없음";
+  loginButton.disabled = authenticated;
+  logoutButton.disabled = !authenticated;
+  apiButton.disabled = !authenticated;
+
+  if (authenticated) {
+    renderJson(tokenMetadata(user));
+  }
+}
+
+async function finishSigninCallback() {
+  const params = new URLSearchParams(window.location.search);
+  const isCallback = window.location.pathname === "/callback.html"
+    && (params.has("code") || params.has("error"));
+
+  if (!isCallback) {
+    return null;
+  }
+
+  const user = await userManager.signinRedirectCallback();
+  window.history.replaceState({}, document.title, "/");
+  return user;
+}
+
+async function callProtectedApi() {
+  if (!currentUser || currentUser.expired) {
+    throw new Error("로그인이 필요합니다.");
+  }
+
+  const response = await fetch(`${backendBaseUrl}/api/me`, {
+    headers: {
+      Authorization: `Bearer ${currentUser.access_token}`,
+    },
+  });
+  const body = await response.json();
+  renderJson({
+    httpStatus: response.status,
+    resourceServerResponse: body,
+    tokenBoundary: tokenMetadata(currentUser),
+  });
+
+  if (!response.ok) {
+    throw new Error(`보호 API가 ${response.status}를 반환했습니다.`);
+  }
+}
+
+loginButton.addEventListener("click", () => userManager.signinRedirect());
+logoutButton.addEventListener("click", () => userManager.signoutRedirect());
+apiButton.addEventListener("click", () => {
+  callProtectedApi().catch((error) => renderJson({ error: error.message }));
+});
+pkceButton.addEventListener("click", () => {
+  createPkcePair()
+    .then(({ verifier, challenge, method }) => renderJson({
+      method,
+      verifierLength: verifier.length,
+      challengeLength: challenge.length,
+      note: "실제 로그인에서는 oidc-client-ts가 같은 S256 단계를 수행합니다.",
+    }))
+    .catch((error) => renderJson({ error: error.message }));
+});
+
+userManager.events.addUserLoaded(renderSession);
+userManager.events.addUserUnloaded(() => renderSession(null));
+userManager.events.addAccessTokenExpired(() => renderSession(null));
+
+try {
+  const callbackUser = await finishSigninCallback();
+  renderSession(callbackUser ?? await userManager.getUser());
+} catch (error) {
+  renderSession(null);
+  renderJson({ error: error.message });
+}

frontend/src/pkce.js

@@ -0,0 +1,26 @@
+function base64Url(bytes) {
+  let binary = "";
+  for (const byte of bytes) {
+    binary += String.fromCharCode(byte);
+  }
+  return btoa(binary)
+    .replaceAll("+", "-")
+    .replaceAll("/", "_")
+    .replace(/=+$/u, "");
+}
+
+export async function createPkcePair(cryptoApi = globalThis.crypto) {
+  const verifierBytes = new Uint8Array(32);
+  cryptoApi.getRandomValues(verifierBytes);
+  const verifier = base64Url(verifierBytes);
+  const digest = await cryptoApi.subtle.digest(
+    "SHA-256",
+    new TextEncoder().encode(verifier),
+  );
+
+  return {
+    verifier,
+    challenge: base64Url(new Uint8Array(digest)),
+    method: "S256",
+  };
+}

frontend/test/pkce.test.mjs

@@ -0,0 +1,18 @@
+import assert from "node:assert/strict";
+import { webcrypto } from "node:crypto";
+import test from "node:test";
+
+globalThis.btoa = (value) => Buffer.from(value, "binary").toString("base64");
+
+const { createPkcePair } = await import("../src/pkce.js");
+
+test("manual PKCE helper creates an RFC 7636 S256 pair", async () => {
+  const pair = await createPkcePair(webcrypto);
+
+  assert.equal(pair.method, "S256");
+  assert.equal(pair.verifier.length, 43);
+  assert.equal(pair.challenge.length, 43);
+  assert.match(pair.verifier, /^[A-Za-z0-9_-]+$/u);
+  assert.match(pair.challenge, /^[A-Za-z0-9_-]+$/u);
+  assert.notEqual(pair.verifier, pair.challenge);
+});

keycloak/import/keycloak-patterns-realm.json

@@ -51,7 +51,22 @@
       "attributes": {
         "pkce.code.challenge.method": "S256",
         "post.logout.redirect.uris": "http://localhost:8088/*##http://127.0.0.1:8088/*"
-      }
+      },
+      "protocolMappers": [
+        {
+          "name": "keycloak-pattern-api-audience",
+          "protocol": "openid-connect",
+          "protocolMapper": "oidc-audience-mapper",
+          "consentRequired": false,
+          "config": {
+            "included.custom.audience": "keycloak-pattern-api",
+            "id.token.claim": "false",
+            "access.token.claim": "true",
+            "userinfo.token.claim": "false",
+            "introspection.token.claim": "true"
+          }
+        }
+      ]
     },
     {
       "clientId": "token-mediating-confidential",

scripts/validate-realm.py

@@ -70,6 +70,18 @@ def validate(path: Path, runtime: bool) -> None:
         spa.get("attributes", {}).get("pkce.code.challenge.method") == "S256",
         "spa-public must enforce PKCE S256",
     )
+    audience_mappers = [
+        mapper
+        for mapper in spa.get("protocolMappers", [])
+        if mapper.get("protocolMapper") == "oidc-audience-mapper"
+    ]
+    if not runtime:
+        require(len(audience_mappers) == 1, "spa-public must declare one audience mapper")
+        require(
+            audience_mappers[0].get("config", {}).get("included.custom.audience")
+            == "keycloak-pattern-api",
+            "spa-public access token must target keycloak-pattern-api",
+        )
 
     for client_id, placeholder in CONFIDENTIAL_CLIENTS.items():
         client = clients[client_id]

scripts/verify-pattern1.sh

@@ -0,0 +1,26 @@
+#!/usr/bin/env sh
+set -eu
+
+if [ ! -f .env ]; then
+  echo "missing .env; copy .env.example and set local-only values" >&2
+  exit 1
+fi
+
+set -a
+. ./.env
+set +a
+
+docker compose down --volumes --remove-orphans
+docker compose up --build -d --wait
+docker compose --profile diagnostics up -d --wait \
+  app-wrong-audience \
+  app-wrong-issuer
+
+npm --prefix e2e ci
+E2E_USERNAME=regular-user \
+E2E_PASSWORD="$REGULAR_USER_PASSWORD" \
+WRONG_AUDIENCE_URL=http://localhost:18081/api/me \
+WRONG_ISSUER_URL=http://localhost:18082/api/me \
+  npm --prefix e2e run test:pattern1
+
+echo "AP1 verified end to end"