Protected Gallery

A personal encrypted media vault for Android. Stores photos, videos and GIFs locally on-device — fully offline, protected by PIN, optionally by biometrics.

Built for personal use. The code is functional and the architecture is straightforward — it does its job well.

     

_{All Media  ·  Import  ·  Settings}

Features

Security

• AES-256-GCM encryption — every file encrypted individually before being written to disk
• Keys stored in Android Keystore — never exposed to JS
• PIN-code protected with brute-force counter
• Optional biometric unlock (fingerprint / face) — hidden button, no visible hint, off by default (tap the lower-left corner)
• Safe Mode — a second independent vault opened with a different PIN; files can be moved between vaults
• FLAG_SECURE — blocks screenshots and app switcher previews at OS level (toggleable)
• Auto-lock after N minutes of inactivity
• Shake-to-lock panic gesture (toggleable)

Media

• Full media viewer with pinch-to-zoom, horizontal swipe between files, swipe-down to dismiss
• Auto-hiding viewer controls — fade out after 2.5 s, tap to toggle; always visible for video
• Daily randomizer tab — shows a random subset of your media each day (toggleable; shows all media when off)
• Filter by type (photo / video / GIF) and sort in All Media
• Import from gallery or via Android share sheet (ACTION_SEND / ACTION_SEND_MULTIPLE)
• Encrypted thumbnail generation on import
• Export — share via system sheet or save directly to Downloads folder
• Trash with 30-day auto-purge
• Archive for files you want to keep but not see daily

Backup

• Encrypted backup to a .pgbak file (ZIP archive with AES-256-GCM encrypted manifest)
• Backup key derived independently from the vault PIN via PBKDF2 — separate password
• Native file copy via react-native-zip-archive — no files loaded into JS heap, no OOM on large vaults
• Full restore from backup file

UX

• Russian / English UI — auto-detected from device locale (CIS → Russian, others → English), switchable in Settings
• Light / Dark / System theme
• Fully offline — zero network requests

Stack

Layer	Library
Framework	React Native 0.81.5 + Expo SDK 54
Native project	expo-dev-client (bare workflow, android/ present)
Encryption	react-native-quick-crypto (AES-256-GCM, PBKDF2)
Key storage	Android Keystore via expo-secure-store
Biometrics	expo-local-authentication
File system	expo-file-system (new File / Directory API)
Backup archive	react-native-zip-archive
Image display	expo-image
Video playback	expo-video
Shake detection	expo-sensors (Accelerometer)
Share / Export	expo-sharing
Save to Downloads	react-native-fs
Gallery import	expo-image-picker
Settings	@react-native-async-storage/async-storage
Safe area	react-native-safe-area-context
i18n	Custom (no external deps) — Intl.DateTimeFormat locale detection

Security model

• Master key generated once, stored encrypted in Android Keystore
• Sub-keys derived per purpose (metadata store, file encryption) via PBKDF2 (200 000 iterations)
• Safe Mode uses a completely separate master key and namespace (vault_safe/)
• Backup key is derived from a separate password — not linked to the vault PIN
• PIN is verified by attempting decryption — no plain PIN stored anywhere
• FLAG_SECURE is set in MainActivity.kt at startup; can be disabled per-user in Settings
• Biometric button is intentionally invisible — its position is known only to the owner

Build

Debug (with Metro, for development)

pnpm exec expo run:android

Release (standalone APK, no Metro)

cd android
./gradlew assembleRelease
adb install -r app/build/outputs/apk/release/app-release.apk

The release APK is signed with the debug keystore by default (signingConfig signingConfigs.debug in build.gradle). For distribution swap in a proper keystore.

Requirements

• Android 10+ (API 29+)
• adb in PATH
• JDK 17+
• New Architecture disabled (newArchEnabled=false in gradle.properties)

Project structure

src/
  crypto/       PIN hashing, master key generation, sub-key derivation
  storage/      Metadata store (encrypted JSON), vault file I/O, backup, settings
  screens/      PinSetup, PinEntry, Daily, Import, Viewer, Settings,
                AllMedia, Trash, Archive, SafeModeSetup, ChangePin, Backup
  components/   TabBar, MediaThumbnail, ZoomableImage, PinPad, SelectionBar
  hooks/        useSelection
  context/      ThemeContext
  i18n/         en.ts, ru.ts, index.ts — locale detection + runtime switching
  utils/        media helpers (formatDuration, formatFileSize, …)
  types/        shared TypeScript types
android/        native Android project (Kotlin, Gradle)

Android native additions

Three things added to the default Expo template:

1. FLAG_SECURE set in MainActivity.kt onCreate — blocks screenshots at the OS window level
2. Share intent handling — processShareIntent() + onNewIntent() in MainActivity.kt receives files from the system share sheet, copies them to cacheDir/pending_share/, JS picks them up on next foreground
3. SecureFlagModule.kt — native Kotlin module that lets JS toggle FLAG_SECURE at runtime (used by the screenshot-blocking toggle in Settings)

License

MIT