Create server.js

server.js

@@ -0,0 +1,39 @@
+const express = require('express');
+const app = express();
+const crypto = require('crypto');
+app.use(express.urlencoded({ extended: true }));
+app.use(express.json());
+
+app.post('/api/getdecryptedkey', (request, response) => {
+    console.log("Request Body", request.body);
+    const privateKey1 = crypto.createPrivateKey({
+        key: Buffer.from(request.body.enc_priv_key, 'base64'),
+        format: 'der',
+        type: 'pkcs8',
+    });
+
+    const publicKey2 = crypto.createPublicKey({
+        key: Buffer.from(request.body.ondc_pub_key, 'base64'),
+        format: 'der',
+        type: 'spki',
+    });
+
+    const sharedKey12 = crypto.diffieHellman({
+        privateKey: privateKey1,
+        publicKey: publicKey2,
+    });
+
+    const iv = Buffer.alloc(0); // ECB doesn't use IV
+    const decipher = crypto.createDecipheriv('aes-256-ecb', sharedKey12, iv);
+
+    let decrypted = decipher.update(request.body.challenge, 'base64', 'utf8');
+    decrypted += decipher.final('utf8');
+    console.log('Decrypted crypto key:', decrypted);
+    response.json({ decrypted_key: decrypted });
+});
+
+const port = 5000;
+
+app.listen(port, () => {
+  console.log(`Server is running on port ${port}`);
+});