# IoT Security Best Practices

**Meta-Description:** IoT Security implementieren. Device Authentication, Verschlüsselung, Secure Boot und Firmware Updates für sichere IoT-Systeme.

**Keywords:** IoT Security, Device Authentication, TLS, Encryption, Secure Boot, Firmware Update, MQTT Security

---

## Einführung

IoT-Sicherheit ist kritisch – vernetzte Geräte sind potenzielle Angriffsziele. **Device Authentication, Verschlüsselung, Secure Boot** und sichere **Firmware Updates** sind Pflicht für jedes professionelle IoT-System.

---

## IoT Security Layers

```
┌─────────────────────────────────────────────────────────────┐
│              IOT SECURITY ARCHITECTURE                       │
├─────────────────────────────────────────────────────────────┤
│                                                             │
│  Layer 7 - Application Security:                            │
│  ├── Input Validation                                       │
│  ├── API Security (Rate Limiting, Auth)                    │
│  └── Secure Data Handling                                  │
│                                                             │
│  Layer 6 - Identity & Access:                               │
│  ├── Device Authentication (Certificates, Tokens)          │
│  ├── User Authentication (MFA, Passkeys)                   │
│  └── Role-Based Access Control (RBAC)                      │
│                                                             │
│  Layer 5 - Communication Security:                          │
│  ├── TLS 1.3 Encryption                                    │
│  ├── mTLS (Mutual TLS)                                     │
│  └── VPN / Private Networks                                │
│                                                             │
│  Layer 4 - Network Security:                                │
│  ├── Firewalls / Segmentation                              │
│  ├── Intrusion Detection (IDS)                             │
│  └── Traffic Monitoring                                    │
│                                                             │
│  Layer 3 - Device Security:                                 │
│  ├── Secure Boot                                           │
│  ├── Hardware Security Module (HSM)                        │
│  ├── Firmware Signing                                      │
│  └── Secure Storage (Encrypted)                            │
│                                                             │
│  Layer 2 - Physical Security:                               │
│  ├── Tamper Detection                                      │
│  ├── Secure Enclosure                                      │
│  └── Debug Port Disable                                    │
│                                                             │
│  Compliance: NIST, ISO 27001, IEC 62443, GDPR              │
│                                                             │
└─────────────────────────────────────────────────────────────┘
```

---

## Device Authentication

```typescript
// lib/device-auth.ts
import crypto from 'crypto';
import jwt from 'jsonwebtoken';

interface DeviceCredentials {
  deviceId: string;
  certificate: string;
  privateKey: string;
}

interface DeviceToken {
  deviceId: string;
  iat: number;
  exp: number;
  capabilities: string[];
}

class DeviceAuthenticator {
  private caCertificate: string;
  private jwtSecret: string;

  constructor(caCertPath: string, jwtSecret: string) {
    this.caCertificate = require('fs').readFileSync(caCertPath, 'utf8');
    this.jwtSecret = jwtSecret;
  }

  // X.509 Certificate-based Authentication
  verifyCertificate(clientCert: string): boolean {
    try {
      const cert = new crypto.X509Certificate(clientCert);
      const caCert = new crypto.X509Certificate(this.caCertificate);

      // Verify certificate chain
      if (!cert.verify(caCert.publicKey)) {
        return false;
      }

      // Check expiration
      const now = new Date();
      if (now < new Date(cert.validFrom) || now > new Date(cert.validTo)) {
        return false;
      }

      // Check revocation (in production: check CRL/OCSP)
      // ...

      return true;
    } catch (error) {
      console.error('Certificate verification failed:', error);
      return false;
    }
  }

  // Extract Device ID from Certificate
  extractDeviceId(clientCert: string): string | null {
    try {
      const cert = new crypto.X509Certificate(clientCert);
      // CN (Common Name) enthält Device ID
      const cnMatch = cert.subject.match(/CN=([^,]+)/);
      return cnMatch ? cnMatch[1] : null;
    } catch {
      return null;
    }
  }

  // JWT Token Generation für Devices
  generateDeviceToken(deviceId: string, capabilities: string[]): string {
    const payload: Omit<DeviceToken, 'iat' | 'exp'> = {
      deviceId,
      capabilities
    };

    return jwt.sign(payload, this.jwtSecret, {
      expiresIn: '24h',
      issuer: 'iot-platform',
      audience: 'iot-devices'
    });
  }

  // Token Verification
  verifyDeviceToken(token: string): DeviceToken | null {
    try {
      return jwt.verify(token, this.jwtSecret, {
        issuer: 'iot-platform',
        audience: 'iot-devices'
      }) as DeviceToken;
    } catch {
      return null;
    }
  }

  // Challenge-Response Authentication
  generateChallenge(): { challenge: string; expiresAt: Date } {
    const challenge = crypto.randomBytes(32).toString('hex');
    const expiresAt = new Date(Date.now() + 5 * 60 * 1000); // 5 Minuten

    return { challenge, expiresAt };
  }

  verifyChallenge(
    challenge: string,
    response: string,
    devicePublicKey: string
  ): boolean {
    try {
      const verify = crypto.createVerify('SHA256');
      verify.update(challenge);

      return verify.verify(devicePublicKey, response, 'base64');
    } catch {
      return false;
    }
  }
}

// API Key Authentication (für einfachere Devices)
interface APIKeyConfig {
  deviceId: string;
  apiKey: string;
  createdAt: Date;
  lastUsed?: Date;
  rateLimit: number;
}

class APIKeyAuthenticator {
  private keys: Map<string, APIKeyConfig> = new Map();

  generateKey(deviceId: string, rateLimit: number = 100): string {
    const apiKey = `iot_${crypto.randomBytes(24).toString('hex')}`;

    this.keys.set(apiKey, {
      deviceId,
      apiKey,
      createdAt: new Date(),
      rateLimit
    });

    return apiKey;
  }

  validateKey(apiKey: string): APIKeyConfig | null {
    const config = this.keys.get(apiKey);

    if (!config) {
      return null;
    }

    // Update last used
    config.lastUsed = new Date();

    return config;
  }

  revokeKey(apiKey: string): void {
    this.keys.delete(apiKey);
  }
}
```

---

## TLS/mTLS Communication

```typescript
// lib/secure-mqtt.ts
import mqtt from 'mqtt';
import fs from 'fs';
import tls from 'tls';

interface SecureMQTTConfig {
  brokerUrl: string;
  caCert: string;
  clientCert: string;
  clientKey: string;
  clientId: string;
}

function createSecureMQTTClient(config: SecureMQTTConfig): mqtt.MqttClient {
  return mqtt.connect(config.brokerUrl, {
    clientId: config.clientId,
    protocol: 'mqtts',
    protocolVersion: 5,  // MQTT 5.0

    // TLS Options
    ca: fs.readFileSync(config.caCert),
    cert: fs.readFileSync(config.clientCert),
    key: fs.readFileSync(config.clientKey),

    // Strict verification
    rejectUnauthorized: true,
    checkServerIdentity: (hostname, cert) => {
      // Custom hostname verification if needed
      return tls.checkServerIdentity(hostname, cert);
    },

    // Connection Options
    keepalive: 60,
    reconnectPeriod: 5000,
    connectTimeout: 30000,

    // Clean Session (MQTT 5.0)
    clean: true,
    properties: {
      sessionExpiryInterval: 0
    }
  });
}

// HTTPS Server mit mTLS
import https from 'https';
import express from 'express';

function createSecureServer(
  app: express.Application,
  caCert: string,
  serverCert: string,
  serverKey: string
) {
  return https.createServer({
    ca: fs.readFileSync(caCert),
    cert: fs.readFileSync(serverCert),
    key: fs.readFileSync(serverKey),

    // Require client certificates (mTLS)
    requestCert: true,
    rejectUnauthorized: true,

    // Minimum TLS version
    minVersion: 'TLSv1.3',

    // Cipher Suites (only strong ciphers)
    ciphers: [
      'TLS_AES_256_GCM_SHA384',
      'TLS_CHACHA20_POLY1305_SHA256',
      'TLS_AES_128_GCM_SHA256'
    ].join(':')
  }, app);
}
```

---

## Secure Data Storage

```typescript
// lib/secure-storage.ts
import crypto from 'crypto';
import { promisify } from 'util';

const scrypt = promisify(crypto.scrypt);

interface EncryptedData {
  iv: string;
  data: string;
  tag: string;
  salt: string;
}

class SecureStorage {
  private masterKey: Buffer | null = null;

  // Key Derivation von Password/PIN
  async deriveKey(password: string, salt: Buffer): Promise<Buffer> {
    return scrypt(password, salt, 32) as Promise<Buffer>;
  }

  // Initialize mit Master Key
  async initialize(masterPassword: string): Promise<void> {
    const salt = crypto.randomBytes(32);
    this.masterKey = await this.deriveKey(masterPassword, salt);
  }

  // AES-256-GCM Encryption
  encrypt(plaintext: string): EncryptedData {
    if (!this.masterKey) {
      throw new Error('Storage not initialized');
    }

    const iv = crypto.randomBytes(16);
    const salt = crypto.randomBytes(32);

    const cipher = crypto.createCipheriv('aes-256-gcm', this.masterKey, iv);

    let encrypted = cipher.update(plaintext, 'utf8', 'hex');
    encrypted += cipher.final('hex');

    const tag = cipher.getAuthTag();

    return {
      iv: iv.toString('hex'),
      data: encrypted,
      tag: tag.toString('hex'),
      salt: salt.toString('hex')
    };
  }

  // Decryption
  decrypt(encryptedData: EncryptedData): string {
    if (!this.masterKey) {
      throw new Error('Storage not initialized');
    }

    const iv = Buffer.from(encryptedData.iv, 'hex');
    const tag = Buffer.from(encryptedData.tag, 'hex');

    const decipher = crypto.createDecipheriv('aes-256-gcm', this.masterKey, iv);
    decipher.setAuthTag(tag);

    let decrypted = decipher.update(encryptedData.data, 'hex', 'utf8');
    decrypted += decipher.final('utf8');

    return decrypted;
  }

  // Secure Credential Storage
  async storeCredentials(
    deviceId: string,
    credentials: Record<string, string>
  ): Promise<EncryptedData> {
    const data = JSON.stringify({ deviceId, credentials, timestamp: Date.now() });
    return this.encrypt(data);
  }
}

// Hardware Security Module (HSM) Integration
interface HSMConfig {
  slotId: number;
  pin: string;
  modulePath: string;
}

class HSMIntegration {
  // Für echte HSM-Integration: PKCS#11 Library verwenden
  // z.B. graphene-pk11, pkcs11js

  async sign(data: Buffer, keyLabel: string): Promise<Buffer> {
    // HSM signing operation
    throw new Error('Implement with actual HSM library');
  }

  async verify(
    data: Buffer,
    signature: Buffer,
    keyLabel: string
  ): Promise<boolean> {
    // HSM verification
    throw new Error('Implement with actual HSM library');
  }

  async generateKeyPair(keyLabel: string): Promise<{ publicKey: string }> {
    // Generate key pair in HSM (private key never leaves HSM)
    throw new Error('Implement with actual HSM library');
  }
}
```

---

## Secure Firmware Updates

```typescript
// lib/firmware-update.ts
import crypto from 'crypto';
import fs from 'fs';
import { pipeline } from 'stream/promises';

interface FirmwareMetadata {
  version: string;
  releaseDate: string;
  sha256: string;
  signature: string;
  size: number;
  minVersion: string;
  deviceModels: string[];
}

class SecureFirmwareUpdater {
  private signingPublicKey: string;

  constructor(publicKeyPath: string) {
    this.signingPublicKey = fs.readFileSync(publicKeyPath, 'utf8');
  }

  // Firmware Signatur verifizieren
  verifySignature(firmwarePath: string, signature: string): boolean {
    const firmware = fs.readFileSync(firmwarePath);

    const verify = crypto.createVerify('SHA256');
    verify.update(firmware);

    return verify.verify(this.signingPublicKey, signature, 'base64');
  }

  // Firmware Hash verifizieren
  verifyHash(firmwarePath: string, expectedHash: string): boolean {
    const firmware = fs.readFileSync(firmwarePath);
    const hash = crypto.createHash('sha256').update(firmware).digest('hex');

    return hash === expectedHash;
  }

  // Firmware Download mit Verification
  async downloadFirmware(
    url: string,
    metadata: FirmwareMetadata,
    targetPath: string
  ): Promise<boolean> {
    const response = await fetch(url);

    if (!response.ok) {
      throw new Error(`Download failed: ${response.status}`);
    }

    // Streaming Download mit Hash-Berechnung
    const hash = crypto.createHash('sha256');
    const fileStream = fs.createWriteStream(targetPath);

    const reader = response.body?.getReader();
    if (!reader) throw new Error('No response body');

    let downloadedSize = 0;

    while (true) {
      const { done, value } = await reader.read();

      if (done) break;

      hash.update(value);
      fileStream.write(value);
      downloadedSize += value.length;
    }

    fileStream.end();

    // Size Check
    if (downloadedSize !== metadata.size) {
      fs.unlinkSync(targetPath);
      throw new Error('Size mismatch');
    }

    // Hash Check
    const actualHash = hash.digest('hex');
    if (actualHash !== metadata.sha256) {
      fs.unlinkSync(targetPath);
      throw new Error('Hash mismatch');
    }

    // Signature Check
    if (!this.verifySignature(targetPath, metadata.signature)) {
      fs.unlinkSync(targetPath);
      throw new Error('Signature verification failed');
    }

    return true;
  }

  // Version Check
  shouldUpdate(
    currentVersion: string,
    newVersion: string,
    minVersion: string
  ): boolean {
    const current = this.parseVersion(currentVersion);
    const target = this.parseVersion(newVersion);
    const min = this.parseVersion(minVersion);

    // Current version must be >= minVersion for update
    if (this.compareVersions(current, min) < 0) {
      return false;
    }

    // Only update if target is newer
    return this.compareVersions(target, current) > 0;
  }

  private parseVersion(version: string): number[] {
    return version.split('.').map(Number);
  }

  private compareVersions(a: number[], b: number[]): number {
    for (let i = 0; i < Math.max(a.length, b.length); i++) {
      const av = a[i] || 0;
      const bv = b[i] || 0;
      if (av > bv) return 1;
      if (av < bv) return -1;
    }
    return 0;
  }
}

// OTA Update API
import express from 'express';

const firmwareRouter = express.Router();

// GET /api/firmware/check?model=xxx&version=1.0.0
firmwareRouter.get('/check', async (req, res) => {
  const { model, version } = req.query;

  // Check for available updates
  const latestFirmware = await getLatestFirmware(model as string);

  if (!latestFirmware) {
    return res.json({ updateAvailable: false });
  }

  const updater = new SecureFirmwareUpdater('./keys/firmware-signing.pub');

  const shouldUpdate = updater.shouldUpdate(
    version as string,
    latestFirmware.version,
    latestFirmware.minVersion
  );

  res.json({
    updateAvailable: shouldUpdate,
    ...(shouldUpdate && { firmware: latestFirmware })
  });
});
```

---

## Input Validation & Sanitization

```typescript
// lib/input-validation.ts
import { z } from 'zod';

// Schema für Sensor-Daten
const SensorDataSchema = z.object({
  device_id: z.string()
    .min(1)
    .max(64)
    .regex(/^[a-zA-Z0-9_-]+$/),

  timestamp: z.string()
    .datetime()
    .refine(
      (ts) => new Date(ts) <= new Date(),
      'Timestamp cannot be in the future'
    ),

  temperature: z.number()
    .min(-50)
    .max(100)
    .optional(),

  humidity: z.number()
    .min(0)
    .max(100)
    .optional(),

  battery: z.number()
    .min(0)
    .max(100)
    .optional()
});

// Schema für Device Commands
const DeviceCommandSchema = z.object({
  action: z.enum(['restart', 'update', 'configure', 'reset']),
  target: z.string().min(1).max(64),
  payload: z.record(z.unknown()).optional()
}).refine(
  (data) => {
    // Dangerous actions require additional validation
    if (data.action === 'reset') {
      return data.payload?.confirm === true;
    }
    return true;
  },
  'Reset action requires confirmation'
);

// Middleware für Input Validation
import { Request, Response, NextFunction } from 'express';

function validateInput(schema: z.ZodType<any>) {
  return (req: Request, res: Response, next: NextFunction) => {
    try {
      req.body = schema.parse(req.body);
      next();
    } catch (error) {
      if (error instanceof z.ZodError) {
        return res.status(400).json({
          error: 'Validation failed',
          details: error.errors
        });
      }
      next(error);
    }
  };
}

// Rate Limiting
import rateLimit from 'express-rate-limit';

const deviceRateLimit = rateLimit({
  windowMs: 60 * 1000, // 1 Minute
  max: 60, // 60 Requests pro Minute
  keyGenerator: (req) => req.headers['x-device-id'] as string || req.ip,
  handler: (req, res) => {
    res.status(429).json({
      error: 'Rate limit exceeded',
      retryAfter: 60
    });
  }
});
```

---

## Security Monitoring

```typescript
// lib/security-monitoring.ts

interface SecurityEvent {
  timestamp: Date;
  eventType: string;
  severity: 'low' | 'medium' | 'high' | 'critical';
  deviceId?: string;
  sourceIp?: string;
  details: Record<string, any>;
}

class SecurityMonitor {
  private events: SecurityEvent[] = [];

  // Authentication Failure
  logAuthFailure(deviceId: string, reason: string, sourceIp: string): void {
    this.logEvent({
      eventType: 'auth_failure',
      severity: 'medium',
      deviceId,
      sourceIp,
      details: { reason }
    });

    // Check for brute force
    this.checkBruteForce(deviceId, sourceIp);
  }

  // Anomaly Detection
  logAnomaly(deviceId: string, anomalyType: string, value: any): void {
    this.logEvent({
      eventType: 'anomaly',
      severity: 'medium',
      deviceId,
      details: { anomalyType, value }
    });
  }

  // Firmware Tampering
  logTamperAttempt(deviceId: string, details: Record<string, any>): void {
    this.logEvent({
      eventType: 'tamper_attempt',
      severity: 'critical',
      deviceId,
      details
    });

    // Immediate alert
    this.sendAlert({
      type: 'tamper_attempt',
      deviceId,
      details
    });
  }

  private logEvent(event: Omit<SecurityEvent, 'timestamp'>): void {
    const fullEvent: SecurityEvent = {
      ...event,
      timestamp: new Date()
    };

    this.events.push(fullEvent);

    // In production: send to SIEM
    console.log('Security Event:', JSON.stringify(fullEvent));
  }

  private checkBruteForce(deviceId: string, sourceIp: string): void {
    const recentFailures = this.events.filter(e =>
      e.eventType === 'auth_failure' &&
      e.timestamp > new Date(Date.now() - 5 * 60 * 1000) &&
      (e.deviceId === deviceId || e.sourceIp === sourceIp)
    );

    if (recentFailures.length >= 5) {
      this.logEvent({
        eventType: 'brute_force_detected',
        severity: 'high',
        deviceId,
        sourceIp,
        details: { failureCount: recentFailures.length }
      });

      // Block IP/Device
      this.blockSource(sourceIp, deviceId);
    }
  }

  private blockSource(ip: string, deviceId: string): void {
    // Implement blocking logic
    console.log(`Blocking IP: ${ip}, Device: ${deviceId}`);
  }

  private sendAlert(alert: Record<string, any>): void {
    // Send to Slack, PagerDuty, etc.
    console.log('ALERT:', alert);
  }
}
```

---

## Security Checklist

| Category | Requirement | Priority |
|----------|------------|----------|
| **Authentication** | Certificate-based device auth | High |
| **Authentication** | No default credentials | Critical |
| **Encryption** | TLS 1.3 for all communications | High |
| **Encryption** | Data at rest encryption | High |
| **Firmware** | Signed firmware updates | Critical |
| **Firmware** | Secure boot chain | High |
| **Network** | Network segmentation | Medium |
| **Network** | Firewall rules | High |
| **Monitoring** | Security event logging | High |
| **Monitoring** | Anomaly detection | Medium |
| **Compliance** | Regular security audits | High |

---

## Fazit

IoT Security erfordert:

1. **Defense in Depth**: Mehrere Sicherheitsebenen
2. **Strong Authentication**: Zertifikate statt Passwörter
3. **Encryption**: TLS everywhere
4. **Secure Updates**: Signierte Firmware

Sicherheit ist keine Option – sie ist Pflicht.

---

## Bildprompts

1. "IoT security layers diagram, defense in depth concept"
2. "Secure device authentication flow, certificate exchange"
3. "Security monitoring dashboard with alerts and events"

---

## Quellen

- [IoT Device Security Best Practices 2026](https://www.jaycon.com/iot-device-security-best-practices/)
- [ConnectWise IoT Security Guide](https://www.connectwise.com/blog/how-to-secure-iot-devices)
- [Fortinet IoT Best Practices](https://www.fortinet.com/resources/cyberglossary/iot-best-practices)
- [Azure IoT Security](https://learn.microsoft.com/en-us/azure/iot/iot-overview-security)
