TB

Trezor Bridge — Secure Device Communication

Presentation · Overview · Best practices · Troubleshooting

Author: Trezor Security Team · Updated guide

This presentation explains what Trezor Bridge is, why it matters for secure device communication, how it works under the hood, and practical guidance for users and integrators. It uses clear headings (h1–h5) and example snippets so you can paste the HTML into docs or slides.

What is Trezor Bridge?

Definition

Trezor Bridge is a small local application that facilitates secure, browser-to-device communication between desktop browsers and Trezor hardware wallets. It replaces older connection methods and provides a consistent transport layer across operating systems.

Key purpose

Enables standard web apps to detect and communicate with Trezor devices.
Acts as a lightweight intermediary to avoid direct USB permission issues in browsers.
Improves user experience and compatibility for wallet apps and dApps.

How it works (high level)

Architecture

Trezor Bridge listens on localhost and exposes a secure, authenticated HTTP/HTTPS endpoint. Browser extensions or web apps use standardized APIs to call Bridge, which forwards those requests over a secure channel to the attached Trezor device via USB.

Transport flow (simplified)

Web app initiates a session using Bridge’s local endpoint.
Bridge validates the request origin and establishes a session.
Bridge sends USB control and data frames to the Trezor device.
Device signs/returns data; Bridge forwards response to the web app.

Example:

curl --request POST http://127.0.0.1:21325/bridge/command \
  --header 'Content-Type: application/json' \
  --data '{"method":"enumerate","params":{}}'

Security model

Principles

The Bridge design follows three core security principles:

Least privilege

Bridge exposes only minimal endpoints needed for device enumeration and commands. It avoids broad system access and enforces origin checks where applicable.

Local-only transport

Bridge listens on the loopback interface by default (e.g., 127.0.0.1). It is not a remote or cloud service — communications remain on the user's machine.

User consent

Every transaction that requires signatures is shown on-device and must be approved by the user, preserving the hardware wallet's trust model even if a host machine is compromised.

Installation & updates

Where to get Bridge

Official homepage Trezor Bridge download Get started guide Support center

Best practices

Always download Bridge from the official Trezor domain above.
Keep Bridge updated — updates include security fixes and compatibility improvements.
Verify checksums or signatures when provided for installation packages.

Developer integration

APIs and libraries

Developers should use Trezor Connect and official libraries to interact with Bridge rather than implementing raw USB logic. This ensures compatibility and reduces risk.

Recommended flow

Use Trezor Connect in your web app.
Detect Bridge locally and prompt the user to install if not present.
Handle errors gracefully and display clear instructions.

Resources:

https://docs.trezor.io/
https://github.com/trezor

Troubleshooting

Common issues & fixes

Device not detected

Check USB cable and port; use a data cable (not charge-only).
Restart Bridge or reinstall from the official download page.
Verify OS permissions — some systems require allowing USB access.

Browser prompts

Modern browsers can change behavior around native messaging and local endpoints. If Bridge appears blocked, review browser settings or update the browser.

Privacy considerations

What Bridge does not do

It does not transmit your private keys off the device.
It does not collect or send transaction details to third parties by default.

Telemetry & opt-in

Any telemetry or optional reporting must be explicitly visible to the user during installation — consult the support pages for current policies.

Official links & further reading

Download Bridge Getting started Support center Developer docs Trezor GitHub Firmware repo Trezor Blog Trezor Twitter Firmware & updates Security center

(Ten official links above — copy these to your resource list or slide deck.)

Quick checklist for users

Before connecting

Download Bridge from the official page.
Use a known-good USB cable and port.
Update your Trezor device firmware through official channels.

When approving transactions, always verify the on-device details — not the host screen.

Closing notes

Trezor Bridge is a pragmatic tool created to make desktop interactions with hardware wallets reliable and secure. It preserves the core security model — keeping private keys on-device while providing a smooth developer and user experience. Use official downloads, follow the checklist, and prefer official libraries for integration.