Trezor Bridge — The Secure Gateway to Your Hardware Wallet™

Overview

Trezor Bridge is a small but powerful application that acts as the **secure gateway** between your web browser and your Trezor hardware wallet. It enables encrypted communication, ensures integrity checks, and abstracts away low-level USB protocols so that interacting with your hardware wallet becomes seamless and safeguarded. In short, Bridge bridges the gap—hence the name—by orchestrating all necessary background communication so that you can manage your crypto assets with confidence and convenience.

Architecture & Components

The architecture of Trezor Bridge consists of multiple layers:

Device Driver Interface

At the lowest level, Bridge interacts with USB transport drivers to detect the hardware wallet device, initiate secure sessions, and manage low‑level message framing. This module is engineered for cross-platform compatibility (Windows, macOS, Linux).

Encryption & Session Management

The session manager negotiates symmetric keys, sets up message counters, and ensures every message is integrity‑protected via HMAC or equivalent. Replay attacks, tampering, and message duplication are all mitigated through this layer.

RPC & Message Marshaling

Bridge also provides an RPC (Remote Procedure Call) layer. When your browser uses the WebUSB or native extension to send commands (e.g. “get public key,” “sign transaction”), Bridge serializes them, wraps them with the appropriate envelope, and forwards them to the device, and vice versa.

Security Mechanisms

Security is foundational to Bridge. Below are its core protections:

Integrity Verification

Bridge verifies each message with checksums and cryptographic signatures. If any message is altered during transit, Bridge discards it and raises an alert.

Firmware Compatibility Check

Bridge cross-checks the device’s firmware version and API compatibility before permitting operations. If your device is running outdated or unsupported firmware, Bridge refuses to proceed, forcing you to update.

Operating System Isolation

Bridge runs as a local background application (or daemon) isolated from browser processes. This isolation reduces the risk that malicious browser code can tamper with the communication channel.

User Confirmation & PIN Code

Even though Bridge passes commands, the user must confirm sensitive operations directly on the Trezor hardware device, and provide PIN / passphrase when required. Bridge never intermediates or stores these secrets.

User Experience & Updates

A core pillar of Trezor Bridge is **usability**. Below are features and practices that enhance the experience:

Automatic Updates

Bridge includes an auto‑updater that periodically checks for security patches, compatibility tweaks, and protocol revisions. This ensures that your bridge remains resilient against newly discovered vulnerabilities.

Cross‑Platform Compatibility

Whether you are on Windows, macOS, or Linux, Bridge delivers a consistent interface and behavior. It detects your OS, installs the correct binary, and sets up the necessary drivers all under the hood.

Error Reporting & Diagnostics

When things go wrong (e.g. communication failure, device not found), Bridge offers detailed error codes, diagnostic logs, and a guided troubleshooting flow. This helps you or support to identify and fix the issue quickly.

Browser Integration

Bridge works hand in hand with browser UIs (WebUSB support or Trezor’s extension). You only see familiar wallet interfaces (like Trezor Suite), while Bridge handles the invisible plumbing behind the scenes.