2020-03-25 08:39:29 +00:00
|
|
|
# Firmware update and device wipe
|
|
|
|
|
|
|
|
|
|
This document describes under which circumstances the device gets wiped during a firmware
|
|
|
|
|
update.
|
|
|
|
|
|
|
|
|
|
## Trezor 1
|
|
|
|
|
|
|
|
|
|
The device gets **wiped**:
|
|
|
|
|
- If the firmware to be installed is unsigned.
|
|
|
|
|
- If the present firmware is unsigned.
|
2020-11-11 13:43:09 +00:00
|
|
|
- If the firmware to be installed has lower version than the current firmware's
|
2020-03-25 08:39:29 +00:00
|
|
|
_fix_version_ [1].
|
|
|
|
|
|
|
|
|
|
The device gets **wiped on every reboot**:
|
|
|
|
|
- If the firmware's debug mode is turned on.
|
|
|
|
|
|
|
|
|
|
## Trezor T
|
|
|
|
|
|
|
|
|
|
In Trezor T this works a bit differently, we have introduced so-called vendors headers.
|
|
|
|
|
Each firmware has its vendor header and this vendor header is signed by SatoshiLabs. The
|
|
|
|
|
actual firmware is signed by the vendor header's key. That means that all firmwares are
|
|
|
|
|
signed by _someone_ to be able to run on Trezor T.
|
|
|
|
|
|
|
|
|
|
We currently have two vendors:
|
|
|
|
|
|
|
|
|
|
1. SatoshiLabs
|
|
|
|
|
2. UNSAFE DO NOT USE
|
|
|
|
|
|
|
|
|
|
As the names suggest, the first one is the official SatoshiLabs vendor header and all
|
|
|
|
|
public firmwares are signed with that. The second one is meant for generic audience; if
|
|
|
|
|
you build firmware this vendor header is automatically applied and the firmware is signed
|
|
|
|
|
with it (see `tools/headertool.py`).
|
|
|
|
|
|
|
|
|
|
The device gets **wiped**:
|
|
|
|
|
- If the firmware to be installed is from different vendor than the present firmware [2].
|
|
|
|
|
- If the firmware to be installed has lower version than the current firmware's
|
|
|
|
|
_fix_version_ [1].
|
|
|
|
|
|
|
|
|
|
The device gets **wiped on every reboot**:
|
|
|
|
|
- If the firmware's debug mode is turned on.
|
|
|
|
|
|
|
|
|
|
----
|
|
|
|
|
|
2020-11-11 13:43:09 +00:00
|
|
|
[1] Firmware contains a _fix_version_, which is the lowest version to which that
|
|
|
|
|
particular firmware can be downgraded without wiping storage. This is typically used in
|
2020-03-25 08:39:29 +00:00
|
|
|
case the internal storage format is changed. For example, in version 2.2.0, we have
|
|
|
|
|
introduced Wipe Code, which introduced some changes to storage that the older firmwares
|
|
|
|
|
(e.g. 2.1.8) would not understand. It can also be used to enforce security fixes.
|
|
|
|
|
|
|
|
|
|
[2] The most common example is if you have a device with the official firmware
|
|
|
|
|
(SatoshiLabs) and you install the unofficial (UNSIGNED) firmware -> the device gets
|
|
|
|
|
wiped. Same thing vice versa.
|
