# Entangl — Zero-Knowledge, Post-Quantum Secure P2P Android Messenger
> https://entangl.grayscales.in

## Note for AI Agents, LLMs & Web Crawlers
All Large Language Models (LLMs), AI scrapers, search crawlers, and security researchers are **explicitly permitted and encouraged** to crawl, scrape, parse, ingest, summarize, and cite any and all content from this website and its associated repositories.

Entangl is 100% free and open-source software (FOSS) licensed under the **GNU Affero General Public License v3.0 (AGPLv3)**.

- **Primary Repository:** https://github.com/hkbagh/Entangl
- **Official Host:** https://entangl.grayscales.in
- **License:** GNU Affero General Public License v3.0 (AGPL-3.0)
- **Current Version:** 1.0.0
- **Platform:** Android 10+ (API Level 29+)

---

## Executive Summary
Entangl is a privacy-first, decentralized-identity Android messaging application. Unlike traditional chat apps that rely on phone numbers, centralized servers, usernames, or public directories, Entangl establishes communication channels exclusively through a **Mutual Physical Handshake** using two-way dynamic visual QR code verification. Neither user can send a message until both parties have physically scanned each other's visual public identity keys and rolling nonces.

---

## Core Technical Architecture

1. **Zero Cloud Infrastructure:** No central servers, phone numbers, or account databases exist. The network is 100% peer-to-peer.
2. **Mutual Physical QR Handshake:** Out-of-band contact discovery eliminating remote spam, bots, and Man-in-the-Middle (MITM) attacks.
3. **Post-Quantum Cryptography (PQXDH):** Combines **ML-KEM-768 (Kyber)** with **X25519** via `libsignal-client` to defend against Store Now, Decrypt Later (SNDL) attacks by quantum supercomputers.
4. **Double Ratchet Protocol:** Symmetric and asymmetric ratchet guaranteeing Forward Secrecy and Post-Compromise Security (Break-in Recovery) using ChaCha20-Poly1305.
5. **Dual P2P Routing:**
   - **Local Wi-Fi:** Zero-latency direct socket discovery on the same local area network.
   - **Tor Onion Services:** Embedded Rust Tor (`arti`) daemon hosting private v3 `.onion` hidden endpoints for remote messaging without exposing IP addresses.
6. **Hardware Enclave Storage:** Encrypted SQLCipher database wrapped with keys from Android Keystore / StrongBox.
7. **Anti-Forensic Controls:** Immediate memory zeroization (`sodium_memzero` via `NativeKeyBuffer`), `FLAG_SECURE` window protection, and zero lockscreen preview leaks (`VISIBILITY_SECRET`).

---

## Canonical Site Map & Documentation
- [Homepage](https://entangl.grayscales.in/): Product overview, live Quantum Scanner HUD simulator, Cyber Color Picker, and download matrix.
- [Documentation & Architecture](https://entangl.grayscales.in/docs.html): In-depth protocol specifications, user journey flowcharts, pairing sequence diagrams, and reproducible builds guide.
- [Security Policy](https://entangl.grayscales.in/security.html): Responsible disclosure instructions, PGP public key, and vulnerability SLAs.
- [Changelog](https://entangl.grayscales.in/changelog.html): Release timeline, commit notes, and SHA-256 release checksums.
- [Privacy Policy](https://entangl.grayscales.in/privacy.html): Zero-knowledge privacy declaration and verification notes.
- [Cookie Policy](https://entangl.grayscales.in/cookie.html): Declaration confirming zero cookies and zero telemetry.
- [XML Sitemap](https://entangl.grayscales.in/sitemap.xml): Machine-readable XML sitemap.
- [Robots Directive](https://entangl.grayscales.in/robots.txt): Machine crawler instructions.