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🔒 Security & Crypto
💬 Messaging
🎨 Interface
🔒 Protection
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┌──────────────────────────────────────────────────┐
│ UI Layer │
│ Fragments · ViewModels · Adapters │
├──────────────────────────────────────────────────┤
│ Repository Layer │
│ ChatRepository — single source of truth │
├────────────────┬────────────────┬────────────────┤
│ Room DB │ Crypto │ Firebase │
│ (SQLCipher) │ PQXDH + DR │ Relay + FCM │
└────────────────┴────────────────┴────────────────┘
📖 Details — Full Architecture · Crypto Protocol · Project Structure
# 1. Clone
git clone https://github.com/DevBot667/SecureChat.git
cd SecureChat
# 2. Add google-services.json to app/ (see docs/SETUP-en.md)
# 3. Build
./gradlew assembleDebug📖 Full Guide — Installation & Firebase Config
| Measure | Status |
|---|---|
| E2E Encryption (PQXDH: X25519 + ML-KEM-1024 + AES-256-GCM / ChaCha20) | ✅ |
| Double Ratchet with PFS + healing | ✅ |
| Memory zeroing (intermediate keys) | ✅ |
| Atomic sending (ratchet + Firebase) | ✅ |
| Conversation Mutex (thread-safe) | ✅ |
| SQLCipher (local DB AES-256 encrypted) | ✅ |
| Metadata hardening (trial decryption) | ✅ |
| senderUid HMAC-SHA256 hashed per conversation | ✅ |
| Fixed-size message padding (anti traffic analysis) | ✅ |
| Delete-after-delivery (Firebase auto-cleanup) | ✅ |
| Configurable dummy traffic (cover traffic) | ✅ |
| E2E file sharing (AES-256-GCM + Firebase Storage) | ✅ |
| PBKDF2 PIN (600K iterations + salt) | ✅ |
| R8/ProGuard obfuscation + complete log stripping (d/v/i/w/e/wtf) | ✅ |
| Fingerprint emojis 96-bit anti-MITM + QR code SHA-256 scanner | ✅ |
| App Lock (PIN + biometrics) | ✅ |
| Restrictive Firebase security rules | ✅ |
| BIP-39 backup/restore (24 words) | ✅ |
allowBackup=false, zero sensitive logs |
✅ |
| Material Design 3 — full migration of all 5 themes | ✅ |
| Inline attachment icons with animation (Session-style) | ✅ |
| Android 13+ permissions (READ_MEDIA_IMAGES/AUDIO) | ✅ |
| Predictive back gesture (enableOnBackInvokedCallback) | ✅ |
| Built-in Tor routing (SOCKS5 + VPN TUN + libtor.so) | ✅ |
| Tor bootstrap screen (choice + progress + 5 themes) | ✅ |
| Tor toggle in Security Settings + reconnect | ✅ |
| Per-conversation dummy traffic | ✅ |
| Ed25519 per-message signatures (anti-forgery) | ✅ |
| PQXDH: X25519 + ML-KEM-1024 (post-quantum resistance) | ✅ |
| SPQR: ML-KEM re-encapsulation every 10 messages | ✅ |
| ChaCha20-Poly1305 alternative (auto hardware AES detection) | ✅ |
| Deferred PQXDH upgrade (rootKey-only, zero desync) | ✅ |
| StrongBox hardware key storage (when available) | ✅ |
| DeviceSecurityManager (StrongBox probe + user profile) | ✅ |
| QR deep link v2 (X25519 + ML-KEM + name, auto-fill) | ✅ |
| displayName hidden from Firebase (zero server-side PII) | ✅ |
| Independent fingerprint verification per user | ✅ |
| Verification system messages + clickable link | ✅ |
| lastDeliveredAt (skip already-processed messages on restart) | ✅ |
| Delete-after-failure (cleanup failed messages from Firebase) | ✅ |
| Atomic dual-listener deduplication (ConcurrentHashMap) | ✅ |
| Signing key cleanup on account deletion | ✅ |
| One-shot photos (view once, 2-phase secure deletion) | ✅ |
| QR code fingerprint scanner (SHA-256 hex, CustomScannerActivity) | ✅ |
| BIP-39 autocomplete 24-word grid (restore redesign) | ✅ |
| Forgot PIN (recovery via mnemonic phrase) | ✅ |
| V3.4.1 Security Audit — 42+ vulnerabilities fixed | ✅ |
| Firebase rules: write-once (signing_keys, mlkem_keys, inbox) | ✅ |
| senderUid/ciphertext/iv/createdAt validation in Firebase rules | ✅ |
| HKDF memory zeroing (IKM, PRK, expandInput) | ✅ |
| MnemonicManager memory zeroing (encode + decode) | ✅ |
| FLAG_SECURE (MainActivity, LockScreen, RestoreFragment, dialogs) | ✅ |
| Tapjacking protection (filterTouchesWhenObscured) | ✅ |
| usesCleartextTraffic=false (zero HTTP traffic) | ✅ |
| Deep link hardening (whitelist, limits, anti-injection) | ✅ |
| Clipboard EXTRA_IS_SENSITIVE + 30s auto-clear | ✅ |
| SecureFileManager (2-pass wipe: random + zeros) | ✅ |
| Opaque FCM payload (zero metadata in push notifications) | ✅ |
| Firebase Storage: delete restricted to uploader only | ✅ |
| ML-KEM size + Base64 client-side validation | ✅ |
| FirebaseRelay.sendMessage input validation (require guards) | ✅ |
| Cloud Function: regex validation senderUid + conversationId | ✅ |
📖 Full Analysis —
SECURITY.md· Crypto Protocol
| Version | Theme | Status |
|---|---|---|
| V1 | Core — E2E, contacts, chats, push, fingerprint, SQLCipher, App Lock, ephemeral | ✅ Done |
| V2 | Crypto Upgrade — Full Double Ratchet X25519, native Curve25519 | ✅ Done |
| V2.1 | Account Lifecycle — BIP-39 backup, restore, delete, dead convo | ✅ Done |
| V2.2 | UI Modernization — 5 themes, animations, CoordinatorLayout, zero hardcoded colors | ✅ Done |
| V3 | Security Hardening — R8, delete-after-delivery, padding, HMAC UID, PBKDF2, dummy traffic, E2E files | ✅ Done |
| V3.1 | Settings Redesign — Signal-like settings, 6-digit PIN, Privacy sub-screen, PIN coroutines | ✅ Done |
| V3.2 | Ed25519 Signing — Per-message signatures, ✅/ |
✅ Done |
| V3.3 | Material 3 + Tor + Attachment UX — M3 migration, full Tor integration, Session-style inline icons, Android 13+ permissions, log hardening | ✅ Done |
| V3.4 | PQXDH + Security — Post-quantum ML-KEM-1024, deep link v2, QR name auto-fill, displayName hidden from Firebase, DeviceSecurityManager StrongBox, independent fingerprint verification, system messages, PQXDH desync fix, dual-listener fix, lastDeliveredAt | ✅ Done |
| V3.4.1 | One-Shot + UX + Security Audit — Ephemeral photos, BIP-39 grid, QR fingerprint, 29 layout audit, forgot PIN, comprehensive security audit (42+ fixes): Firebase rules write-once, HKDF/mnemonic memory zeroing, FLAG_SECURE, deep link hardening, SecureFileManager, opaque FCM, Storage owner-only delete, input validation | ✅ Done |
| V3.5 | SPQR + ChaCha20 + Threat Model — PQ Triple Ratchet (ML-KEM re-encapsulation every 10 msgs), ChaCha20-Poly1305 alternative (auto hardware detection), documented threat model in SECURITY.md | ✅ Done |
| V3.6 | Planned — App disguise + cover screen, Dual PIN, panic button, E2E voice messages, sealed sender, reply/quote | 🔜 |
📖 Details — Full Changelog
- Fork the repo
- Create your branch (
git checkout -b feature/my-feature) - Commit (
git commit -m 'Add my feature') - Push (
git push origin feature/my-feature) - Open a Pull Request
⚠️ For any crypto modification, please open an issue first to discuss it.
| Document | Content |
|---|---|
| Architecture | Patterns, layers, request flows, lifecycle |
| Crypto Protocol | X25519, Double Ratchet, fingerprint, threat model |
| Setup | Prerequisites, Firebase, build, dependencies |
| Structure | Full project tree |
| Changelog | V1 → V3.5 history |
| Security | Full audit, known limitations |
This project is licensed under GPLv3. See the Terms of Service before use.
Provided for educational purposes. Use it as a definitive base to understand E2E encryption on mobile.
⚠️ Disclaimer : This software is a personal and educational project. The cryptographic implementation has NOT been audited by a third-party security firm. No guarantee of absolute security is provided. Do not rely on it as your sole means of secure communication in critical situations. Use of this software is at your own risk. See TERMS.md.
"Your messages, your keys, your privacy."