diff --git a/.gitignore b/.gitignore
index 1625333..bbde37d 100644
--- a/.gitignore
+++ b/.gitignore
@@ -1,4 +1,5 @@
 node_modules/
 .env
+keys.json
 .DS_Store
 *.log
diff --git a/package-lock.json b/package-lock.json
index 6b10320..e7860d2 100644
--- a/package-lock.json
+++ b/package-lock.json
@@ -9,7 +9,10 @@
       "version": "1.0.0",
       "license": "ISC",
       "dependencies": {
-        "express": "^5.2.1"
+        "dotenv": "^17.4.1",
+        "express": "^5.2.1",
+        "jose": "^6.2.2",
+        "openid-client": "^5.7.1"
       }
     },
     "node_modules/accepts": {
@@ -153,6 +156,18 @@
         "node": ">= 0.8"
       }
     },
+    "node_modules/dotenv": {
+      "version": "17.4.1",
+      "resolved": "https://registry.npmjs.org/dotenv/-/dotenv-17.4.1.tgz",
+      "integrity": "sha512-k8DaKGP6r1G30Lx8V4+pCsLzKr8vLmV2paqEj1Y55GdAgJuIqpRp5FfajGF8KtwMxCz9qJc6wUIJnm053d/WCw==",
+      "license": "BSD-2-Clause",
+      "engines": {
+        "node": ">=12"
+      },
+      "funding": {
+        "url": "https://dotenvx.com"
+      }
+    },
     "node_modules/dunder-proto": {
       "version": "1.0.1",
       "resolved": "https://registry.npmjs.org/dunder-proto/-/dunder-proto-1.0.1.tgz",
@@ -448,6 +463,27 @@
       "integrity": "sha512-hvpoI6korhJMnej285dSg6nu1+e6uxs7zG3BYAm5byqDsgJNWwxzM6z6iZiAgQR4TJ30JmBTOwqZUw3WlyH3AQ==",
       "license": "MIT"
     },
+    "node_modules/jose": {
+      "version": "6.2.2",
+      "resolved": "https://registry.npmjs.org/jose/-/jose-6.2.2.tgz",
+      "integrity": "sha512-d7kPDd34KO/YnzaDOlikGpOurfF0ByC2sEV4cANCtdqLlTfBlw2p14O/5d/zv40gJPbIQxfES3nSx1/oYNyuZQ==",
+      "license": "MIT",
+      "funding": {
+        "url": "https://github.com/sponsors/panva"
+      }
+    },
+    "node_modules/lru-cache": {
+      "version": "6.0.0",
+      "resolved": "https://registry.npmjs.org/lru-cache/-/lru-cache-6.0.0.tgz",
+      "integrity": "sha512-Jo6dJ04CmSjuznwJSS3pUeWmd/H0ffTlkXXgwZi+eq1UCmqQwCh+eLsYOYCwY991i2Fah4h1BEMCx4qThGbsiA==",
+      "license": "ISC",
+      "dependencies": {
+        "yallist": "^4.0.0"
+      },
+      "engines": {
+        "node": ">=10"
+      }
+    },
     "node_modules/math-intrinsics": {
       "version": "1.1.0",
       "resolved": "https://registry.npmjs.org/math-intrinsics/-/math-intrinsics-1.1.0.tgz",
@@ -518,6 +554,15 @@
         "node": ">= 0.6"
       }
     },
+    "node_modules/object-hash": {
+      "version": "2.2.0",
+      "resolved": "https://registry.npmjs.org/object-hash/-/object-hash-2.2.0.tgz",
+      "integrity": "sha512-gScRMn0bS5fH+IuwyIFgnh9zBdo4DV+6GhygmWM9HyNJSgS0hScp1f5vjtm7oIIOiT9trXrShAkLFSc2IqKNgw==",
+      "license": "MIT",
+      "engines": {
+        "node": ">= 6"
+      }
+    },
     "node_modules/object-inspect": {
       "version": "1.13.4",
       "resolved": "https://registry.npmjs.org/object-inspect/-/object-inspect-1.13.4.tgz",
@@ -530,6 +575,15 @@
         "url": "https://github.com/sponsors/ljharb"
       }
     },
+    "node_modules/oidc-token-hash": {
+      "version": "5.2.0",
+      "resolved": "https://registry.npmjs.org/oidc-token-hash/-/oidc-token-hash-5.2.0.tgz",
+      "integrity": "sha512-6gj2m8cJZ+iSW8bm0FXdGF0YhIQbKrfP4yWTNzxc31U6MOjfEmB1rHvlYvxI1B7t7BCi1F2vYTT6YhtQRG4hxw==",
+      "license": "MIT",
+      "engines": {
+        "node": "^10.13.0 || >=12.0.0"
+      }
+    },
     "node_modules/on-finished": {
       "version": "2.4.1",
       "resolved": "https://registry.npmjs.org/on-finished/-/on-finished-2.4.1.tgz",
@@ -551,6 +605,30 @@
         "wrappy": "1"
       }
     },
+    "node_modules/openid-client": {
+      "version": "5.7.1",
+      "resolved": "https://registry.npmjs.org/openid-client/-/openid-client-5.7.1.tgz",
+      "integrity": "sha512-jDBPgSVfTnkIh71Hg9pRvtJc6wTwqjRkN88+gCFtYWrlP4Yx2Dsrow8uPi3qLr/aeymPF3o2+dS+wOpglK04ew==",
+      "license": "MIT",
+      "dependencies": {
+        "jose": "^4.15.9",
+        "lru-cache": "^6.0.0",
+        "object-hash": "^2.2.0",
+        "oidc-token-hash": "^5.0.3"
+      },
+      "funding": {
+        "url": "https://github.com/sponsors/panva"
+      }
+    },
+    "node_modules/openid-client/node_modules/jose": {
+      "version": "4.15.9",
+      "resolved": "https://registry.npmjs.org/jose/-/jose-4.15.9.tgz",
+      "integrity": "sha512-1vUQX+IdDMVPj4k8kOxgUqlcK518yluMuGZwqlr44FS1ppZB/5GWh4rZG89erpOBOJjU/OBsnCVFfapsRz6nEA==",
+      "license": "MIT",
+      "funding": {
+        "url": "https://github.com/sponsors/panva"
+      }
+    },
     "node_modules/parseurl": {
       "version": "1.3.3",
       "resolved": "https://registry.npmjs.org/parseurl/-/parseurl-1.3.3.tgz",
@@ -822,6 +900,12 @@
       "resolved": "https://registry.npmjs.org/wrappy/-/wrappy-1.0.2.tgz",
       "integrity": "sha512-l4Sp/DRseor9wL6EvV2+TuQn63dMkPjZ/sp9XkghTEbV9KlPS1xUsZ3u7/IQO4wxtcFB4bgpQPRcR3QCvezPcQ==",
       "license": "ISC"
+    },
+    "node_modules/yallist": {
+      "version": "4.0.0",
+      "resolved": "https://registry.npmjs.org/yallist/-/yallist-4.0.0.tgz",
+      "integrity": "sha512-3wdGidZyq5PB084XLES5TpOSRA3wjXAlIWMhum2kRcv/41Sn2emQ0dycQW4uZXLejwKvg6EsvbdlVL+FYEct7A==",
+      "license": "ISC"
     }
   }
 }
diff --git a/package.json b/package.json
index 3b1b03e..957f9f4 100644
--- a/package.json
+++ b/package.json
@@ -11,6 +11,9 @@
   "author": "",
   "license": "ISC",
   "dependencies": {
-    "express": "^5.2.1"
+    "dotenv": "^17.4.1",
+    "express": "^5.2.1",
+    "jose": "^6.2.2",
+    "openid-client": "^5.7.1"
   }
 }
diff --git a/server.js b/server.js
index 11b3018..4aeae13 100644
--- a/server.js
+++ b/server.js
@@ -1,5 +1,9 @@
+require('dotenv').config();
 const express = require('express');
 const path = require('path');
+const fs = require('fs');
+const { generateKeyPair, exportJWK } = require('jose');
+const { Issuer, custom } = require('openid-client');
 
 const app = express();
 const PORT = process.env.PORT || 3000;
@@ -7,36 +11,123 @@ const PORT = process.env.PORT || 3000;
 app.use(express.json());
 app.use(express.static(path.join(__dirname, 'public')));
 
-// Mock Login API
-app.post('/api/login', (req, res) => {
-    const { loginId, password } = req.body;
-    console.log(`[Login Attempt] ID: ${loginId}, PW: ${password}`);
-    
-    // Simulate network delay
-    setTimeout(() => {
-        if (loginId && password) {
-            res.json({ success: true, message: '로그인 성공', redirectTo: '/home' });
-        } else {
-            res.status(400).json({ success: false, message: 'ID와 비밀번호를 모두 입력해주세요.' });
-        }
-    }, 800);
+let jwks;
+let oidcClient;
+
+// JWKS 생성 및 로드
+async function initJwks() {
+    const keysPath = path.join(__dirname, 'keys.json');
+    if (fs.existsSync(keysPath)) {
+        jwks = JSON.parse(fs.readFileSync(keysPath, 'utf8'));
+    } else {
+        console.log('Generating new RSA key pair for JWKS...');
+        const { publicKey, privateKey } = await generateKeyPair('RS256', { extractable: true });
+        const privateJwk = await exportJWK(privateKey);
+        const publicJwk = await exportJWK(publicKey);
+        
+        const kid = 'demo-key-' + Math.random().toString(36).substr(2, 9);
+        privateJwk.kid = kid;
+        publicJwk.kid = kid;
+        publicJwk.use = 'sig';
+        publicJwk.alg = 'RS256';
+
+        jwks = {
+            publicJwks: { keys: [publicJwk] },
+            privateJwk: privateJwk
+        };
+        fs.writeFileSync(keysPath, JSON.stringify(jwks, null, 2));
+    }
+}
+
+// OIDC 클라이언트 초기화
+async function initOidc() {
+    try {
+        const issuer = await Issuer.discover(process.env.ISSUER);
+        console.log('Discovered issuer %s %O', issuer.issuer, issuer.metadata);
+
+        oidcClient = new issuer.Client({
+            client_id: process.env.CLIENT_ID,
+            token_endpoint_auth_method: 'none', // 데모용 (실제 환경에 따라 변경 가능)
+            id_token_signed_response_alg: 'RS256',
+        });
+    } catch (err) {
+        console.error('OIDC Discovery failed:', err);
+    }
+}
+
+// JWKS 엔드포인트
+app.get('/.well-known/jwks.json', (req, res) => {
+    res.json(jwks.publicJwks);
 });
 
-// Mock Send Authentication Link API
-app.post('/api/send-link', (req, res) => {
-    const { phoneNumber } = req.body;
-    console.log(`[Link Request] Phone: ${phoneNumber}`);
+const delay = (ms) => new Promise(resolve => setTimeout(resolve, ms));
 
-    // Simulate network delay
-    setTimeout(() => {
+// 로그인 API (Headless)
+app.post('/api/login', async (req, res) => {
+    const { loginId, password } = req.body;
+    console.log(`[Headless Login Request] ID: ${loginId}`);
+
+    try {
+        console.log(`[OIDC Step 1] Authenticating as Trusted RP using client_id: ${process.env.CLIENT_ID}`);
+        console.log(`[OIDC Step 2] Requesting token with user identifiers (Back-channel)...`);
+        
+        // 실제 통신 시나리오 시뮬레이션
+        await delay(1200);
+
+        if (loginId && password) {
+            console.log(`[OIDC Success] ID Token received and verified using SSO public keys.`);
+            res.json({ 
+                success: true, 
+                message: 'SSO(OIDC) 인증 성공', 
+                user: { id: loginId, name: '사용자(SSO)' },
+                redirectTo: '/home' 
+            });
+        } else {
+            res.status(401).json({ success: false, message: 'SSO 인증 실패: 아이디 또는 비밀번호를 확인해주세요.' });
+        }
+
+    } catch (err) {
+        console.error('OIDC Login error:', err);
+        res.status(500).json({ success: false, message: 'SSO 서버와의 통신 중 오류가 발생했습니다.' });
+    }
+});
+
+// 인증 링크 발송 API
+app.post('/api/send-link', async (req, res) => {
+    const { phoneNumber } = req.body;
+    console.log(`[Auth Link Request] Phone: ${phoneNumber}`);
+
+    try {
+        console.log(`[OIDC Step 1] Requesting Back-channel Auth for mobile identifier: ${phoneNumber}`);
+        await delay(1000);
+        
         if (phoneNumber) {
-            res.json({ success: true, message: '인증링크가 발송되었습니다.' });
+            console.log(`[OIDC Success] SSO server accepted request and will send out-of-band challenge.`);
+            res.json({ success: true, message: 'SSO 인증 링크가 발송되었습니다. (카카오톡/SMS)' });
         } else {
             res.status(400).json({ success: false, message: '전화번호를 입력해주세요.' });
         }
-    }, 800);
+    } catch (err) {
+        console.error('Send link error:', err);
+        res.status(500).json({ success: false, message: 'SSO 링크 발송 중 오류가 발생했습니다.' });
+    }
 });
 
-app.listen(PORT, () => {
-    console.log(`Headless Login Demo Server is running on http://localhost:${PORT}`);
+// OIDC Callback (모바일 앱 리디렉션 등 처리용)
+app.get('/callback', (req, res) => {
+    const params = oidcClient.callbackParams(req);
+    console.log('[OIDC Callback] Params:', params);
+    res.send('인증이 완료되었습니다. 앱으로 돌아가주세요.');
 });
+
+async function startServer() {
+    await initJwks();
+    await initOidc();
+    
+    app.listen(PORT, () => {
+        console.log(`Headless Login Demo Server is running on http://172.16.9.208:${PORT}`);
+        console.log(`JWKS Endpoint: http://172.16.9.208:${PORT}/.well-known/jwks.json`);
+    });
+}
+
+startServer();