diff --git a/README.md b/README.md
index 960be80..e1c611a 100644
--- a/README.md
+++ b/README.md
@@ -9,6 +9,7 @@ Erster funktionaler Backend-Stand für die Vision:
 - Datenmodell inkl. postalischer Adress-Verifikation (`backend/sql/schema.sql`)
 - Address-Change-Flow mit Briefcode (`/addresses/change-request`, `/addresses/verify`)
 - Kontaktdatenaustausch nach Deal (`/contacts/request`, `/contacts/respond`, `/contacts/deal/:dealId`)
+- Serverseitige AES-256-GCM-Verschlüsselung für Adresse/Telefon (`DATA_ENCRYPTION_KEY`)
 
 ## Start
 
diff --git a/backend/.env.example b/backend/.env.example
index b73887f..f01b507 100644
--- a/backend/.env.example
+++ b/backend/.env.example
@@ -5,3 +5,4 @@ DB_NAME=helpyourneighbour
 DB_USER=helpyourneighbour
 DB_PASSWORD=change-me
 JWT_SECRET=change-me-super-secret
+DATA_ENCRYPTION_KEY=base64-32-byte-key
diff --git a/backend/src/routes/addresses.js b/backend/src/routes/addresses.js
index 2c50115..dfca5dc 100644
--- a/backend/src/routes/addresses.js
+++ b/backend/src/routes/addresses.js
@@ -3,13 +3,14 @@ import { createHash, randomInt } from 'crypto';
 import { z } from 'zod';
 import { pool } from '../db/connection.js';
 import { requireAuth } from '../middleware/auth.js';
+import { encryptText } from '../services/encryption.js';
 
 const router = Router();
 
 const hashCode = (code) => createHash('sha256').update(code).digest('hex');
 
 router.post('/change-request', requireAuth, async (req, res) => {
-  const parsed = z.object({ newAddressEncrypted: z.string().min(10) }).safeParse(req.body);
+  const parsed = z.object({ newAddress: z.string().min(10) }).safeParse(req.body);
   if (!parsed.success) return res.status(400).json({ error: parsed.error.flatten() });
 
   const verificationCode = String(randomInt(100000, 999999));
@@ -18,7 +19,7 @@ router.post('/change-request', requireAuth, async (req, res) => {
   const [result] = await pool.query(
     `INSERT INTO address_change_requests (user_id, new_address_encrypted, verification_code_hash)
      VALUES (?, ?, ?)`,
-    [req.user.userId, parsed.data.newAddressEncrypted, verificationCodeHash]
+    [req.user.userId, encryptText(parsed.data.newAddress), verificationCodeHash]
   );
 
   res.status(201).json({
diff --git a/backend/src/routes/profile.js b/backend/src/routes/profile.js
new file mode 100644
index 0000000..caa8dad
--- /dev/null
+++ b/backend/src/routes/profile.js
@@ -0,0 +1,19 @@
+import { Router } from 'express';
+import { z } from 'zod';
+import { pool } from '../db/connection.js';
+import { requireAuth } from '../middleware/auth.js';
+import { encryptText } from '../services/encryption.js';
+
+const router = Router();
+
+router.post('/phone', requireAuth, async (req, res) => {
+  const parsed = z.object({ phone: z.string().min(6).max(40) }).safeParse(req.body);
+  if (!parsed.success) return res.status(400).json({ error: parsed.error.flatten() });
+
+  const encryptedPhone = encryptText(parsed.data.phone);
+  await pool.query('UPDATE users SET phone_encrypted = ? WHERE id = ?', [encryptedPhone, req.user.userId]);
+
+  res.json({ status: 'updated' });
+});
+
+export default router;
diff --git a/backend/src/server.js b/backend/src/server.js
index 4667534..8e91e75 100644
--- a/backend/src/server.js
+++ b/backend/src/server.js
@@ -6,6 +6,7 @@ import offerRoutes from './routes/offers.js';
 import reviewRoutes from './routes/reviews.js';
 import addressRoutes from './routes/addresses.js';
 import contactRoutes from './routes/contacts.js';
+import profileRoutes from './routes/profile.js';
 
 dotenv.config();
 
@@ -20,6 +21,7 @@ app.use('/offers', offerRoutes);
 app.use('/reviews', reviewRoutes);
 app.use('/addresses', addressRoutes);
 app.use('/contacts', contactRoutes);
+app.use('/profile', profileRoutes);
 
 const port = Number(process.env.PORT || 3000);
 app.listen(port, () => {
diff --git a/backend/src/services/encryption.js b/backend/src/services/encryption.js
new file mode 100644
index 0000000..07b67fb
--- /dev/null
+++ b/backend/src/services/encryption.js
@@ -0,0 +1,39 @@
+import { createCipheriv, createDecipheriv, randomBytes } from 'crypto';
+
+const ALGO = 'aes-256-gcm';
+
+const getKey = () => {
+  const key = process.env.DATA_ENCRYPTION_KEY;
+  if (!key) throw new Error('DATA_ENCRYPTION_KEY is not set');
+
+  const keyBuf = Buffer.from(key, 'base64');
+  if (keyBuf.length !== 32) throw new Error('DATA_ENCRYPTION_KEY must be base64-encoded 32 bytes');
+  return keyBuf;
+};
+
+export const encryptText = (plainText) => {
+  const iv = randomBytes(12);
+  const key = getKey();
+  const cipher = createCipheriv(ALGO, key, iv);
+
+  const encrypted = Buffer.concat([cipher.update(plainText, 'utf8'), cipher.final()]);
+  const tag = cipher.getAuthTag();
+
+  return `${iv.toString('base64')}:${tag.toString('base64')}:${encrypted.toString('base64')}`;
+};
+
+export const decryptText = (payload) => {
+  const [ivB64, tagB64, dataB64] = payload.split(':');
+  if (!ivB64 || !tagB64 || !dataB64) throw new Error('Invalid encrypted payload format');
+
+  const key = getKey();
+  const decipher = createDecipheriv(ALGO, key, Buffer.from(ivB64, 'base64'));
+  decipher.setAuthTag(Buffer.from(tagB64, 'base64'));
+
+  const decrypted = Buffer.concat([
+    decipher.update(Buffer.from(dataB64, 'base64')),
+    decipher.final()
+  ]);
+
+  return decrypted.toString('utf8');
+};