Activity 20: Privacy Implementation - Discovery Challenge

# 1. Install dependencies
npm install --legacy-peer-deps

# 2. Start the app
npx expo start

# 3. Press 'w' for web or scan QR code with Expo Go

// Strip metadata using expo-image-manipulator
static async stripMetadata(uri) {
  const result = await ImageManipulator.manipulateAsync(
    uri,
    [],  // No transformations
    { compress: 0.92, format: ImageManipulator.SaveFormat.JPEG }
  );
  return { success: true, uri: result.uri, metadataStripped: true };
}

// Generate random filename using expo-crypto
static async generateAnonymousFilename() {
  const randomBytes = await Crypto.getRandomBytesAsync(8);
  const hexString = Array.from(randomBytes)
    .map(b => b.toString(16).padStart(2, '0'))
    .join('');
  return `photo_${hexString}.jpg`;
}

const handleShare = async () => {
  // 1. Prepare photo with privacy settings
  const result = await PhotoPrivacyService.createShareableCopy(
    photoUri,
    privacySettings
  );

  // 2. Check if sharing is available
  const isAvailable = await Sharing.isAvailableAsync();

  // 3. Share the photo
  await Sharing.shareAsync(result.uri, { mimeType: 'image/jpeg' });

  // 4. Clean up cache
  await PhotoPrivacyService.cleanupShareCache();
};

// Get saved consents
static async getConsents() {
  const result = await SecureStorageService.getPreference(CONSENT_KEY);
  if (result.success && result.value?.version === CONSENT_VERSION) {
    return { ...this.defaultConsents, ...result.value.consents };
  }
  return null;  // Needs collection
}

// Save user's consent choices
static async saveConsents(consents) {
  const data = {
    version: CONSENT_VERSION,
    consents: { ...this.defaultConsents, ...consents, essential: true },
    consentDate: new Date().toISOString()
  };
  return await SecureStorageService.setPreference(CONSENT_KEY, data);
}

import * as LocalAuthentication from 'expo-local-authentication';

const authenticate = async () => {
  const hasHardware = await LocalAuthentication.hasHardwareAsync();
  if (hasHardware) {
    const result = await LocalAuthentication.authenticateAsync();
    return result.success;
  }
  return false;
};

activity-20-privacy-implementation/
├── App.js                         # Main entry point
├── README.md                      # This file
├── package.json                   # Dependencies
├── services/
│   ├── SecureStorageService.js    # ✅ Complete (secure/async storage)
│   ├── PhotoPrivacyService.js     # ⚠️ TODO 2
│   └── ConsentService.js          # ⚠️ TODO 4
├── components/
│   ├── PhotoCard.js               # ✅ Complete
│   ├── ConsentBanner.js           # ✅ Complete
│   └── PrivacyAwareShare.js       # ⚠️ TODO 3
├── screens/
│   ├── PhotoScreen.js             # ✅ Complete
│   └── PrivacySettingsScreen.js   # ⚠️ TODO 5
└── utils/
    └── SamplePhotos.js            # ✅ Sample data

// In your component or console:
import SecureStorageService from './services/SecureStorageService';

// Test storing sensitive data
await SecureStorageService.setSecure('test_token', 'secret123');
const result = await SecureStorageService.getSecure('test_token');
console.log('Retrieved:', result.value); // Should be 'secret123'

// Clean up
await SecureStorageService.deleteSecure('test_token');