Presentation

Trezor Bridge — Secure Wallet Communication Layer App

A full, colorful HTML presentation about the communication layer that connects desktop apps and web pages with Trezor hardware wallets.

Overview

Trezor Bridge is a small, dedicated communication layer that enables secure and reliable interactions between web pages, desktop applications and Trezor hardware wallets. Acting as an intermediary, Bridge translates high-level JSON-RPC or WebUSB calls into instructions that the Trezor device understands, while enforcing origin checks and access control.

This presentation explains the purpose, components, installation, and security model of Trezor Bridge. It also provides developer guidance for integrating Bridge into wallets and dApps, troubleshooting tips, and hands-on examples. The content below is structured with clear headings (h1–h5) so it can be repurposed for slides or printed handouts.

Key takeaways

  • Trezor Bridge is the trusted local proxy for communicating with Trezor devices.
  • It isolates hardware communication from the browser and provides stable APIs.
  • Bridge enforces origin-based permissions, transport selection and rate-limiting.
  • Developers should prefer standard libraries (eg. trezor-connect) that build on Bridge.

Architecture

Logical components (h3)

Bridge sits locally on the user's machine. Architecturally, it can be broken into three logical pieces:

  1. Transport listener: accepts WebUSB calls and HTTP requests from local clients.
  2. Command processor: translates JSON-RPC requests into Trezor protocol messages.
  3. Device I/O: performs the final encoding and sends low-level packets to the Trezor device over USB / HID.

Data flow (h3)

1) Browser extension or web page issues a request (via trezor-connect or direct WebUSB).
2) Bridge validates origin and permission state.
3) Command processor transforms the high-level call to device-specific protocol messages.
4) Device I/O sends data; Bridge returns result or error back to the client.

Sequence diagram (h4)

Browser / App  -> Bridge: JSON-RPC (getPublicKey)
Bridge         -> Device: Trezor protocol packet
Device         -> Bridge: Signed data
Bridge         -> Browser: JSON response (publicKey)
Why an intermediary?

Direct browser-to-USB communication varies across platforms and browsers. Bridge centralizes compatibility, provides consistent APIs, and offers improved security controls (for example, origin whitelisting and human confirmation prompts).

Security Model

Security is the most important part of Bridge's design. It does not replace device-level protections — user PINs, passphrases, and the device's secure element — but complements them by ensuring that only authorized hosts can talk to a connected Trezor.

Origin verification (h3)

Bridge enforces checks on the calling origin: the web application must present proof of its origin to Bridge and the user must grant permission. This prevents remote sites from silently accessing a local Trezor.

Least privilege (h3)

When possible, requests should specify minimal scopes (for example, readonly key derivation rather than signing) to reduce blast radius in case of compromise.

User prompts & human approval (h4)

Although Bridge can initiate communication, any sensitive operation must be confirmed on the Trezor device itself — the final gatekeeper is the physical device and the user. Bridge passes descriptive information so the device or service can present meaningful prompts.

Transport hardening (h4)

Bridge isolates raw USB/HID access to the local process and keeps cross-origin requests from reaching device firmware without explicit consent.

Installation & Updates

Installing Bridge is straightforward: users download an installer for Windows, macOS, or Linux and run it. Bridge typically runs as a background service and listens on a local port (for the HTTP fallback) and via WebUSB.

Installation steps (h3)

  1. Download the Bridge installer for your OS from the official site.
  2. Run the installer and accept any system prompts (macOS may require additional permission in Security & Privacy).
  3. Open your browser or wallet app and test the device connection.

Automatic updates (h4)

Bridge often updates to improve compatibility and security. Automated updates usually occur via the OS-native installer mechanisms — users should allow updates to keep the communication layer secure.

Unattended / enterprise installs (h5)

For deployments, Bridge can be installed silently using standard packaging tools. Check organization's policy for distributing trusted installers and updating them regularly.

Developer Integration

Developers should not reimplement low-level protocols. Instead, use maintained libraries (e.g., trezor-connect) which speak to Bridge on your behalf and provide friendly APIs for common wallet operations.

Basic example (h3)

// Example: request public key using a JS library
import TrezorConnect from 'trezor-connect';

TrezorConnect.getPublicKey({
  path: "m/44'/0'/0'/0/0",
}).then(response => {
  if (response.success) console.log(response.payload.publicKey);
  else console.error(response.payload.error);
});

Best practices for apps (h4)

Testing & CI (h5)

When adding Bridge integration in CI, mock the Bridge API or use an emulated environment. Hardware tests should be kept as part of a separate integration test-suite.

Troubleshooting

Common issues (h3)

Diagnostic commands (h4)

# On many platforms you can check if the bridge service is running with:
# Linux (systemd): systemctl status trezor-bridge
# macOS: ps aux | grep trezord
# Windows: check Services or Task Manager for "Trezor Bridge"
When to contact support (h5)

If device firmware behaves unexpectedly or Bridge repeatedly fails after updates, collect logs and contact official support channels. Do not share sensitive wallet data — only diagnostic logs and steps to reproduce.

Best Practices & Operational Security

Follow the principle of least privilege, keep Bridge and device firmware updated, and educate users about phishing and origin spoofing.

For end-users (h3)

For integrators (h3)