Security & Safety in Trezor

The purpose of this article is to give a detailed account of the software specifications and security features used by the Trezor Safe 5, Trezor Safe 3, Trezor Model T, and Trezor Model One.

The software used in Trezor devices has always been open-source to be fully auditable. Everyone can look at the code used in Trezor devices and verify its integrity, look for vulnerabilities, or suggest improvements and integrations.

We made Trezor fully transparent to eliminate the inherent need for trust and to share as much of our knowledge and ideas with the broader community.

See the SatoshiLabs Security Philosophy Manifesto for more details on our principles and motivations.

Trezor Safe 7

Operating Systems

Trezor Safe 7 uses several layers of code that work together to check authenticity, enforce security rules, and protect your private keys. These layers load one another in a strict order to ensure only trusted code ever runs on the device.

Boardloader

The boardloader is the write protected, factory embedded code that sits at the foundation of Trezor Safe 7. Its job is to verify the bootloader and prove that the device is genuine.

The boardloader on Trezor Safe 7 is also the first hardware wallet implementation that can verify post quantum signatures, preparing the device for future upgrades when quantum safe cryptography becomes standard.

The boardloader cannot be updated, changed, or removed.

Boardloader key points:

• Embedded and unmodifiable

• Verifies the bootloader

• Uses post quantum verification

• Acts as the root of trust for the device

  Bootloader

  The bootloader installs, updates, and checks the firmware. If the firmware is modified or unofficial, the device will warn the user before running it.

If the device is started without valid firmware, or both buttons are pressed during startup, the bootloader enters firmware update mode.

Bootloader key points:

• Installs, updates, and checks firmware integrity
• Verifies firmware signatures
• Is updatable

Firmware

The firmware is the main software that operates Trezor Safe 7. It handles the interface, wallet logic, security checks, and device features. Any firmware update must be physically confirmed on the device by the user.

Firmware key points:

• Runs all wallet functions
• Verified by the bootloader before execution
• Updated regularly to improve security and usabilit

Keeping your device updated ensures you always have the latest protections.

Authorization

Physical Access

Trezor Safe 7 uses a dual secure element architecture for stronger physical security. It includes:

• TROPIC01, the first open source secure element
• OPTIGA Trust M, used in previous Trezor Safe devices

These chips work together to protect PIN processing, enforce attempt limits, and guard secret material, making physical attacks on the device far more difficult.

Trezor Safe 5

Operating Systems

There are multiple layers of code ensuring the legitimacy and safety of operations executed by your device.

Boardloader

The boardloader is the write-protected, embedded-immutable code of the device. It loads and checks the integrity of the bootloader. It prevents code-based attacks (e.g., BadUSB) and ensures only verified embedded code runs on the device.

The boardloader cannot be updated, modified, or removed.

Boardloader key points:

• Embedded and unmodifiable
• Loads the bootloader and checks its integrity

Bootloader

The bootloader installs, updates, and checks the firmware. If unofficial firmware is detected, the device displays a warning.

If both buttons are pressed or no firmware is present, the device starts in firmware update mode.

Bootloader key points:

• Uploads, updates, and checks firmware integrity
• Is updatable
• Signatures checked by the bootloader

Firmware

Firmware operates the device, executes functions, and maintains security. Updates require physical confirmation on the device.

Firmware key points:

• Operates the device
• Checked by the bootloader
• Regularly updated

Authorization

Physical Access

Trezor devices implement several safety measures to prevent unauthorized access. Notably, Trezor Safe 5 has a dedicated OPTIGA™ Trust M Secure Element, which protects highly sensitive information from hardware and software attacks.

Trezor Safe 3

Operating Systems

There are multiple layers of code ensuring the legitimacy and safety of operations executed by your device.

Boardloader

The boardloader is the write-protected, embedded-immutable code of the device. It loads and checks the integrity of the bootloader.

Boardloader key points:

• Embedded and unmodifiable
• Loads the bootloader and checks its integrity

Bootloader

The bootloader installs, updates, and checks the firmware. If unofficial firmware is detected, the device displays a warning.

Bootloader key points:

• Uploads, updates, and checks firmware integrity
• Is updatable
• Signatures checked by the bootloader

Firmware

Firmware operates the device, executes functions, and maintains security.

Firmware key points:

• Operates the device
• Checked by the bootloader
• Regularly updated

Trezor Model T

Operating Systems

There are multiple layers of code ensuring the legitimacy and safety of operations executed by your device.

Boardloader

The boardloader is a write-protected, embedded-immutable code that loads and checks the integrity of the bootloader.

Boardloader key points:

• Embedded and unmodifiable
• Loads the bootloader and checks its integrity

Bootloader

The bootloader installs, updates, and checks the firmware. If an unofficial firmware is detected, a warning is displayed.

Bootloader key points:

• Uploads, updates, and checks firmware integrity
• Is updatable
• Signatures checked by the bootloader

Firmware

Firmware operates the device, executes functions, and maintains security.

Firmware key points:

• Operates the device
• Checked by the bootloader
• Regularly updated

Trezor Model One

Operating Systems

There are multiple layers of code ensuring the legitimacy and safety of operations executed by your device.

Bootloader

The bootloader installs, updates, and checks the firmware loaded on the device. It verifies the integrity of the firmware and displays a warning if unofficial firmware is detected.

Bootloader key points:

• Uploads, updates, and checks the integrity of the firmware
• Is updatable
• Signatures checked by the bootloader

Firmware

Firmware operates the device, executes functions, and maintains security.

Firmware key points:

• Operates the device
• Checked by the bootloader
• Regularly updated