Introduction
One of the biggest differences between our latest Trezor Safe 3 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 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 3 is the OPTIGATM 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 recovery seed. The trick is to design a mechanism in which the Secure Element doesn’t learn your recovery seed - and that’s what we’ve implemented here.
The Secure Element in the TS3 protects your PIN (without learning it), which releases a secret (stored on the Secure Element), which in turn protects your recovery seed (stored only on the 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 recovery seed, i.e., it never actually knows what your recovery seed is.
Is the Trezor Safe 3 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 recovery seed and keys, remains fully open-source. We've also managed to source the OPTIGATM 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 3 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.
