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Briar

lastmod 2025-03-18created 2025-03-181 edits

Secure messaging anywhere

Censorship-resistant peer-to-peer messaging that bypasses centralized servers. Connect via Bluetooth, Wi-Fi or Tor, with privacy built-in.

About

  • Briar is a messaging app for people who need safe and easy communication, such as activists and journalists
    • Android only. Open source
  • Unlike traditional messaging apps, it does not rely on a central server and syncs directly between users' devices
  • If the internet goes down, it can sync via Bluetooth, Wi-Fi, or memory cards, keeping information flowing even in a crisis
  • When connected to the internet, it syncs via the Tor network, protecting users and their relationships from surveillance
  • Briar Mailbox lets messages be delivered securely even between users who are online at different times

Technical details

  • Briar uses direct encrypted connections between users to prevent surveillance and censorship
  • Typical messaging software relies on central servers, exposing messages and relationships to surveillance
  • Briar can share data via Wi-Fi, Bluetooth, and the internet
  • Briar provides private messages, public forums, and blogs, and protects against the following surveillance and censorship threats:
    • Metadata surveillance: uses the Tor network so that eavesdroppers cannot tell which users are talking to each other
    • Content surveillance: all communication between devices is end-to-end encrypted, protecting content from eavesdropping and tampering
    • Content filtering: end-to-end encryption prevents keyword filtering, and the decentralized design means there is no server to block
    • Takedown orders: every forum subscriber holds a copy of the content, so there is no single point from which to delete posts
    • Denial-of-service attacks: Briar's forums have no central server to attack, and every subscriber can access content even while offline
    • Internet blackouts: Briar can keep information flowing during blackouts via Bluetooth and Wi-Fi

Threat model

  • Briar is designed to resist surveillance and censorship by an adversary with the following capabilities:
    • All long-range communication channels (internet, telephone network, etc.) are comprehensively monitored by the adversary
    • The adversary can block, delay, replay, and modify traffic on long-range communication channels
    • The adversary can monitor short-range communication channels (Bluetooth, WiFi, etc.) to a limited extent
    • The adversary can block, delay, replay, and modify traffic on short-range communication channels to a limited extent
    • The adversary can deploy an unlimited number of devices running Briar
    • Some users can keep their devices secure; in the threat model, those who cannot are considered to be controlled by the adversary
    • The adversary has a limited ability to persuade users to trust the adversary's agents, and the number of social connections between the adversary's agents and the rest of the network is limited
    • The adversary cannot break standard cryptographic primitives

Long-term plans

  • Plans to use Briar's data sync capability to support secure, distributed applications such as crisis mapping and collaborative document editing.
  • The goal is to let people in any country create safe spaces where they can discuss any topic, plan events, and organize social movements.

See also

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author Zer0 sitemap