# Signal Desktop — End-to-End Encrypted Messaging for Desktop

> Signal Desktop is the official desktop client for the Signal private messenger. Built with Electron, it provides end-to-end encrypted messaging, voice notes, group chats, and disappearing messages on Linux, macOS, and Windows.

## Install

Save in your project root:

# Signal Desktop — End-to-End Encrypted Messaging for Desktop

## Quick Use
```bash
# Install via Homebrew (macOS)
brew install --cask signal

# Install via apt (Debian/Ubuntu)
# Add the Signal repository key and source, then:
sudo apt install signal-desktop

# Install via Flatpak (Linux)
flatpak install flathub org.signal.Signal

# Windows: download from https://signal.org/download/
```

## Introduction
Signal Desktop is the official desktop companion to the Signal private messenger. It extends Signal's end-to-end encryption protocol to Linux, macOS, and Windows, allowing you to send and receive messages, media, voice notes, and video calls from your computer. Signal is developed by the non-profit Signal Technology Foundation with a focus on privacy and open-source transparency.

## What Signal Desktop Does
- Sends and receives end-to-end encrypted text, image, video, and voice messages
- Supports group chats with up to 1000 members, all end-to-end encrypted
- Provides disappearing messages with configurable expiration timers
- Syncs message history with a linked mobile device over an encrypted channel
- Enables voice and video calls from the desktop application

## Architecture Overview
Signal Desktop is built with Electron and TypeScript. It uses the Signal Protocol (Double Ratchet algorithm with X3DH key agreement) for end-to-end encryption, implemented via libsignal-client (written in Rust with bindings to Node.js). Messages are stored in a local SQLite database encrypted with SQLCipher. The app communicates with Signal's servers only for message routing and key exchange; servers never have access to plaintext content.

## Self-Hosting & Configuration
- Download official builds from signal.org or install via platform package managers
- Signal Desktop must be linked to an existing Signal mobile account via QR code pairing
- On Linux, official packages are available for Debian/Ubuntu (apt) and Flatpak
- Message data is stored locally and encrypted; no cloud backup of desktop messages exists
- Proxy support is available for users in regions where Signal is blocked

## Key Features
- Uses the Signal Protocol, widely regarded as the gold standard for end-to-end encryption
- Sealed sender feature hides metadata about who is messaging whom from Signal servers
- Built-in note-to-self feature for saving private notes across devices
- Keyboard shortcuts and notification controls for power users
- Full source code is open and auditable under the AGPL-3.0 license

## Comparison with Similar Tools
- **Telegram Desktop** — Faster and more feature-rich for groups, but only Secret Chats are end-to-end encrypted; Signal encrypts everything by default
- **WhatsApp Desktop** — Uses the Signal Protocol but is closed source and owned by Meta with broader data collection
- **Element (Matrix)** — Decentralized and self-hostable; Signal is centralized but simpler to use with stronger default privacy
- **Slack/Discord** — Designed for teams and communities; Signal is designed for private person-to-person and small group messaging
- **Wire** — Also end-to-end encrypted and open source, but has a smaller user base and a commercial focus

## FAQ
**Q: Can I use Signal Desktop without a phone?**
A: No. Signal Desktop must be linked to a Signal account on a mobile device. The phone handles initial registration and key generation.

**Q: Is Signal Desktop open source?**
A: Yes. The full source code is available on GitHub under the AGPL-3.0 license.

**Q: Does Signal Desktop store messages locally?**
A: Yes. Messages are stored in a local SQLCipher-encrypted SQLite database on your computer.

**Q: Can I self-host a Signal server?**
A: The server code is open source, but self-hosting requires maintaining your own infrastructure and would create a separate network incompatible with the main Signal network.

## Sources
- https://github.com/signalapp/Signal-Desktop
- https://signal.org/

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Author: AI Open Source