echo6-docs/docs/matrix/mautrix_signal.md

mautrix-signal Bridge Reference

Deployed: 2026-04-09 (Phase 3)

Updated: 2026-04-09 (Phase 5)

Deployment

• Image: dock.mau.dev/mautrix/signal:v0.2603.0
• Container: mautrix-signal
• Compose: /opt/matrix/docker-compose.yml (same stack as Synapse)
• Config dir: /opt/matrix/mautrix-signal/
• Network: matrix-net (internal only, no host port mapping)
• Appservice port: 29328 (container-internal)

Database

• DB name: mautrix_signal
• DB role: mautrix_signal (NOSUPERUSER, NOCREATEDB, NOCREATEROLE)
• Host: matrix-postgres:5432 (same container as Synapse/MAS)
• Collation: C/C (matches Synapse)

Signal Account

• Phone: +12083080811
• Login ID: 58f99d83-f3a8-487f-a2b7-3d118e236d23
• Matrix user: @matt:echo6.co

Bot

• MXID: @signalbot:echo6.co
• Device ID: UPX4KKLZVY
• Management room: !fDjIRTMjxILVQoAcEN:echo6.co

Encryption

• E2BE: enabled (allow: true, default: true, require: true)
• MSC4190: enabled (required for MAS compatibility)
• Pickle key: auto-generated, stored in config
• Self-sign: true

Synapse Integration

• Registration files: /opt/matrix/synapse/registration.yaml, /opt/matrix/synapse/doublepuppet.yaml
• homeserver.yaml additions:
  • app_service_config_files: [/data/registration.yaml, /data/doublepuppet.yaml]
  • experimental_features.msc3202_transaction_extensions: true
  • experimental_features.msc2409_to_device_messages_enabled: true
• Registration file permissions: 644 (world-readable, Synapse UID 991)

Double Puppeting

• Method: appservice-based (doublepuppet.yaml)
• as_token: configured in bridge config double_puppet.secrets
• Effect: Messages matt sends from Signal appear as @matt:echo6.co in Matrix

MAS Compatibility

• Confirmed working: as_token auth bypasses MAS entirely
• MSC4190: Parsed from registration.yaml io.element.msc4190: true, NOT a homeserver experimental_features flag
• Synapse handles appservice auth independently of MAS token introspection

Autocreate Behavior

• No autocreate toggle exists in bridgev2 signal connector
• portal_create_filter config key is silently stripped on restart
• Old keys (autocreate_group_portal, autocreate_contact_portal) don't exist
• Portals auto-create when incoming Signal messages arrive for untracked groups/DMs
• This is the default and only behavior — cannot be disabled

Permissions

bridge:
  permissions:
    "*": relay
    "echo6.co": user
    "@matt:echo6.co": admin

Backup

• DB dumped by /opt/matrix/scripts/pg_backup.sh (added alongside synapse + mas dumps)
• 14-day retention, daily at 3 AM

Management Commands

Available in management room (!fDjIRTMjxILVQoAcEN:echo6.co):

• !signal help — list commands
• !signal ping-matrix — verify Matrix connectivity
• !signal list-logins — show linked Signal accounts
• !signal sync-portal — force-sync current portal
• !signal id — show bridge IDs for current room
• !signal create-group — create a new Signal group
• !signal start-chat — start a DM with a Signal user
• !signal resolve-identifier — look up a Signal user

NOT available (bridgev2 signal connector doesn't expose):

• list-chats, bridge, create-portal, filter

Provisioning API

• Shared secret: in config.yaml (do NOT log or put in ref files)
• Allow Matrix auth: true
• Debug endpoints: false