Secure Element in Trezor Safe 5 & Trezor Safe 3

Introduction

One of the biggest differences between Trezor Safe Family and the Model One or Model T is the introduction of a dedicated Secure Element. Here we discuss the basic functions of the Secure Element, what it does and doesn’t do, and how our approach doesn’t compromise the open source design of Trezor hardware wallets.

What is a Secure Element and what does it (not) do?

Broadly speaking, the chip performs two key jobs. First, it enhances the physical security of the Trezor Safe 5 and Trezor Safe 3 by adding a layer of safety to the PIN protection mechanism. Second, it plays an important role in verifying the authenticity of your device.

The Secure Element used in the Trezor Safe 5 and Trezor Safe 3 is the OPTIGA^TM Trust M (V3). In effect, it is a chip designed to protect highly sensitive information from software and hardware attacks. In the context of hardware wallets, what you really need to protect is your Wallet Backup (formerly recovery seed). The trick is to design a mechanism in which the Secure Element doesn’t learn your Wallet Backup - and that’s what we’ve implemented here.

The Secure Element in the Trezor Safe 5 and Trezor Safe 3 protects your PIN (without learning it), which releases a secret (stored on the Secure Element), which in turn protects your Wallet Backup (stored only on the Trezor Safe 5 and Trezor Safe 3 general purpose chip, encrypted by both the device PIN and the secret stored on the Secure Element).

We do not run code on the chip itself. The Secure Element simply stores a secret that can be used to decrypt the Wallet Backup i.e., it never actually knows what your Wallet Backup is.

Is the Trezor Safe Family still open source?

Yes. We have worked hard to integrate the Secure Element without sacrificing the transparent design of our devices. Our code, which handles your Wallet Backup and keys, remains fully open-source. We've also managed to source the OPTIGA^TM Trust M (V3) chips from a producer that does not restrict us from freely publishing potential vulnerabilities, so we can stay true to our open source philosophy.

Is the Trezor Safe Family safer than the Model One or Model T?

Having the extra layer of protection afforded by the Secure Element is not a silver bullet. While it provides added security against certain physical attack vectors, we strongly recommend that all Trezor users learn how to safely use a strong passphrase, which offers an un-hackable level of protection to your funds.