mirror of
https://github.com/trezor/trezor-firmware.git
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129 lines
4.6 KiB
Markdown
129 lines
4.6 KiB
Markdown
# Reproducible build
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We want to invite the wider community to participate in the verification of the firmware
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built by Trezor Company. With reasonable effort you should be able to build the firmware
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and verify that it's identical to the official firmware.
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Trezor Firmware uses [Nix](https://nixos.org/), [Poetry](https://python-poetry.org/) and
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[Cargo](https://doc.rust-lang.org/cargo/) to make the build environment deterministic.
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We also provide a Docker-based script so that the build can be performed with a single
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command on usual x86 Linux system.
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## Building
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First you need to determine which *version tag* you want to build:
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* for Trezor One it is `legacy/vX.Y.Z`, e.g. `legacy/v1.10.3`,
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* for newer models, it is `core/vX.Y.Z`, e.g. `core/v2.4.2`.
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Assuming you want to build `core/v2.8.3`:
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1. install [Docker](https://www.docker.com/)
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2. clone the firmware repository: `git clone https://github.com/trezor/trezor-firmware.git`
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3. go into the firmware directory: `cd trezor-firmware`
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4. checkout the version tag: `git checkout core/v2.8.3`
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5. run: `bash build-docker.sh core/v2.8.3`
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After the build finishes the firmware images are located in:
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* `build/legacy/firmware/firmware.bin` and `build/legacy-bitcoinonly/firmware/firmware.bin` for Trezor One,
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* `build/core-<model>/firmware/firmware.bin` and `build/core-<model>-bitcoinonly/firmware/firmware.bin` for later models.
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### Model identifiers
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You can speed up the build process by adding options to the script:
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* `--skip-core` if you are only building for Trezor One,
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* `--skip-legacy --models=A,B,C` to only build for specific model(s) which are not Trezor One.
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The following models are supported:
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* **`T`** - Trezor Model T
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* **`R`** - Trezor Safe 3 rev.A
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* **`T3B1`** - Trezor Safe 3 rev.B
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* **`T3T1`** - Trezor Safe 5
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Examples:
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```sh
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bash build-docker.sh --skip-core legacy/v1.10.3 # build only for Trezor One
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bash build-docker.sh --skip-legacy --models=T3T1 core/v2.8.3 # build only for Trezor Safe 5
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```
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## Verifying
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The result won't be bit-by-bit identical with the official images because the
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official images are signed while local builds aren't.
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### Trezor T and the Safe family
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You can use `trezorctl` to download the official firmware image for your device:
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```sh
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trezorctl firmware download --model t3t1 --version 2.8.3
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```
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Or locate the firmware image in the [Trezor Data repository](https://github.com/trezor/data/tree/master/firmware).
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The firmware binary starts with a [vendor header](../hardware/model-t/boot.md#vendor-header)
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whose size is:
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* Model T: 4608 bytes
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* Safe 3: 512 bytes
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* Safe 5: 1024 bytes
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The vendor header is followed by a [firmware header](../hardware/model-t/boot.md#firmware-header)
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that contains a 65-byte signature at offset `0x3bf` (959 in decimal).
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You will need to calculate the right offset for the signature based on the model:
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* Model T: 4608 + 959 = 5567
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* Safe 3: 512 + 959 = 1471
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* Safe 5: 1024 + 959 = 1983
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Zero out the signature data to obtain an image identical to the one built locally:
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```sh
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OFFSET=<your offset here>
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# the following line removes 65 bytes of signature data from the official firmware
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dd if=/dev/zero of=trezor-t3t1-2.8.3.bin bs=1 seek=$OFFSET count=65 conv=notrunc
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# the following two lines print out the hashes of the firmwares
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sha256sum trezor-t3t1-2.8.3.bin
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sha256sum build/core-T3T1/firmware/firmware.bin
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```
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### Trezor One
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You can use `trezorctl` to download the official firmware image for your device:
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```sh
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trezorctl firmware download --model 1 --version 1.10.3
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```
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Or locate the firmware image in the [Trezor Data repository](https://github.com/trezor/data/tree/master/firmware).
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Official Trezor One firmware older than 1.12 starts with [256-byte legacy
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header](../hardware/model-one/firmware-format.md) used for compatibility with old
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bootloaders. Locally built firmware doesn't have this header.
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```
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# strip legacy header
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tail -c +257 trezor-1.10.3.bin > trezor-1.10.3-nolegacyhdr.bin
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```
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The [v2 header](../hardware/model-one/firmware-format.md#v2-header) has 3x65
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bytes of signature data at offset 0x220. Overwrite by zeros to obtain image
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identical to the one built locally.
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```
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dd if=/dev/zero of=trezor-1.10.3-nolegacyhdr.bin bs=1 seek=544 count=195 conv=notrunc
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sha256sum trezor-1.10.3-nolegacyhdr.bin
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sha256sum build/legacy/firmware/firmware.bin
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```
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_Note: Fingerprints displayed for T1 at the end of `build-docker.sh` do not match fingerprints of
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official firmware due to the legacy header._
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_Note: T1 firmware built this way won't boot because unsigned firmware needs to be built with
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[`PRODUCTION=0`](../legacy/index.md#combining-bootloader-and-firmware-with-various-production-settings-signedunsigned)._
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