Signal

The Signal bridge allows you to link Matrix rooms with Signal chats. Users who are active on Matrix can also communicate with participants on Signal without using the Signal app directly. This also creates seamless integration in groups where individual members are on Signal or Matrix, for example, and allows you to collaborate across different platforms.

We currently host the Signal bridge from mautrix.

Features of the bridge

Features

You can find the official feature list at mautrix.

Here is a selection of the key features:

Legend:

• M→S Matrix to Signal
• S→M Signal to Matrix
• M↔S Bidirectional

• Message content (text, formatting, files, no locations) M↔S
• Edit and delete messages M↔S
• Reactions to messages M↔S
• Profile pictures of users M↔S
• Typing notifications M↔S
• Custom emojis/stickers and polls S→M
• Read receipts (partial) M↔S
• Messages from unauthenticated Matrix users via relay bot M→S

Prerequisites

To use the Signal bridge, you must meet the following requirements:

• Matrix account on an instance hosted by us with the bridges option booked
• Signal account to be linked to the bridge

Setup

Setting up the Signal bridge takes just a few steps:

• Start a new direct message in Matrix with @signalbot:bridges.osrx.chat or click here.
• Use help to display a list of available Signal bridge commands.
• First, log in with your Signal account (command login).
• The Signal bridge will now start synchronizing your chats. This can take a while depending on the number of current requests. Private chats are usually synchronized and displayed when new messages are received.

FAQ

• How can I exclude individual chats from syncing with Matrix? - Leave the chat room. You can have the room recreated later using the bot command create-portal.
• How can I delete all Signal chats in Matrix? - Send logout to the Signal bridge bot. You will then be removed from all Signal chats automatically, and the data will be completely deleted a few days later.
• How many chats and messages are synchronized? - Unfortunately, Signal does not support the synchronization of old messages, as new encryption keys are negotiated when the bridge is set up. A room is automatically created in Matrix for incoming messages.
• How long is my data stored? - The bridge server stores text messages for 24 hours and media data for one year. After that, they are deleted. They may remain in server backups for a certain period of time. Please note: to transfer messages between Matrix and Signal, the bridge has to decrypt them on the bridge server and process them in plain text. End-to-end encryption ends there, so the data stored on the bridge server is not protected in the same way as with true end-to-end encryption.

Security and data protection

Security and the protection of your personal data are important and sometimes difficult issues when using bridges. The Signal bridge connects two systems with different data protection guidelines and standards. It is important to consider the following aspects when bridging:

• Privacy policies: We provide you with the Signal bridge as a processor. As the controller, you must be familiar with Signal's privacy policy and know how data is processed. By using the Signal bridge, data will be transferred from one system to another, which affects the applicability of the respective data protection guidelines. Furthermore, data may be transferred to countries with different levels of data protection.
• Encryption: On the Matrix side, chats via the Signal bridge are always end-to-end encrypted - we enforce this in the bridge configuration. This encryption ends at the bridge: it has to decrypt the messages and process them in plain text in order to transfer them between Matrix and Signal. From there on, the protection level of Signal applies, which does not necessarily match that of Matrix.

Requests / comments / notes

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