Trezor Bridge — Secure Connection for Your Trezor

Overview

Trezor Bridge is a background application that enables modern browsers and desktop apps to communicate with Trezor hardware wallets (Trezor One, Trezor Model T) over a secure, local connection. It acts as a bridge between USB device endpoints and web-based wallet interfaces such as the official Trezor Suite or WebUSB-enabled web apps. Bridge handles device discovery, permission management, and encrypted transport so your private keys never leave the device.

Why Bridge exists

Historically browsers used a variety of USB access methods. Trezor Bridge provides a stable, cross-platform layer that:

• Enables both legacy desktop apps and web apps to talk to the Trezor device.
• Abstracts OS-specific USB permission handling and driver requirements.
• Improves security by limiting network exposure — the Bridge listens only on localhost (loopback) and requires user confirmation on the device for signing actions.

Installation & Setup

Quick steps

1. Download the official Trezor Bridge installer from the Trezor website and run it.
2. Restart your browser if prompted (some browsers require a restart to detect the Bridge service).
3. Connect your Trezor device via USB (or USB-C) and unlock it with your PIN.
4. Open your wallet application (Trezor Suite or a compatible web wallet) and follow on-screen prompts to pair.

Notes on platforms

Bridge supports major operating systems (Windows, macOS, Linux). On Windows, the installer may add a lightweight service; on Linux you may need to add udev rules. Always use the official installer and verify the download source.

Example (Linux udev rule snippet):
SUBSYSTEM=="usb", ATTR{idVendor}=="534c", MODE="0660", GROUP="plugdev"

Tip: If your OS offers WebUSB and you prefer that workflow, newer browser versions may allow direct device access without Bridge. For consistency and multi-app compatibility, Bridge is still commonly recommended.

Security Considerations

What Bridge does not do

Bridge does not hold or transmit private keys. All sensitive operations (seed generation, signing transactions) happen on the Trezor device itself. Bridge simply relays encrypted requests and responses between your browser/app and the device.

Attack surface & best practices

• Keep Bridge updated. Security fixes may be released; update from official sources.
• Verify downloads. Use the official website or verified repositories to avoid malicious installers.
• Limit network exposure. Bridge binds to localhost by design — check firewall rules if concerned.
• Confirm device actions. Always verify the transaction details on the Trezor's screen before approving.
• Use a secure host. Run Bridge on a machine you control; avoid public or untrusted computers.

Troubleshooting

Common issues & fixes

Device not detected

• Ensure the device is unlocked with your PIN.
• Try a different USB cable or port — prefer a data-capable cable (not charge-only).
• Restart Bridge or your machine; check that the Bridge process is running.

Browser can't connect

• Some browsers require a restart after Bridge installation.
• Check browser permissions for USB or WebUSB if using direct access.

Driver issues (Windows)

When drivers are missing, re-run the official installer. For advanced users, device manager can show driver status and allow manual installation.

Advanced debugging

Bridge logs (if enabled) can reveal errors. On Linux, systemd logs or journalctl might also show USB subsystem issues. Always redact sensitive information if sharing logs with support.

Typical Workflow (What Happens When You Connect)

1. Your browser or desktop app sends a request to localhost where the Bridge listens.
2. Bridge checks device presence and forwards the request to the Trezor over USB.
3. The Trezor displays the operation details (e.g., transaction amount, recipient) for user confirmation.
4. After you confirm, the Trezor signs the request and returns the signed data via Bridge to the app.

Minimal conceptual exchange:
1. App -> Bridge: "List devices" 
2. Bridge -> App: "Trezor at /dev/ttyUSB0"
3. App -> Bridge: "Sign transaction #123"
4. User approves on device UI
5. Device -> Bridge -> App: "Signed payload"

FAQ — Quick Questions

Do I need Bridge for every wallet?

Not always. Some modern browsers and wallet apps support WebUSB or native protocols. Bridge offers the widest compatibility across tools and is recommended for general use.

Is Bridge safe to run on a connected machine?

Yes — provided you install the official release, keep your OS and Bridge up-to-date, and avoid running untrusted software on the same host.

Can Bridge be used over a network?

No. Bridge is designed to operate on localhost only. It does not expose remote network interfaces for device control.

Best Practices & Final Recommendations

• Always verify transaction details on your Trezor screen before approving.
• Download Bridge only from the official source and verify any checksums/signatures the vendor provides.
• Keep a clean, updated host environment — patch regularly and avoid installing untrusted software.
• Consider dedicating a device or VM for high-value operations if you perform custody for many accounts.
• Use passphrases and backups responsibly — never share recovery seeds or passphrases with anyone.