Skycoin hardware wallet

Table of contents

• Overview
• FAQ
• Install tools
• Build instructions:
  • Build and run emulator
  • Build a bootloader
  • Build a bootloader with memory protection enabled
  • Build a firmware
  • Sign firmware
  • Combine bootloader and firmware
  • Combine a memory protected bootloader and firmware
• Development guidelines
  • Versioning policies
    • Firmware version scheme
    • Bootloader version scheme
    • Versioning combined binary builds
    • Versioning libraries
  • Running tests
    • Generating tests code coverage
  • Validate the TRNG
    • Files description
  • Releases
    • Skycoin firmware releases
    • Update the version
    • Pre-release testing
    • Creating release builds

Overview

This folder provides a firmware implementing skycoin features, and tools to test it.

The firmware itself is under tiny-firmware folder. The firmware had been copied and modified from this repository.

The skycoin-api folder contains the definition of the functions implementing the skycoin features.

The skycoin-hw-cli defines golang functions that communicate with the firmware.

There is also a javascript API.

Follow up the wiki to keep track of project advancement.

FAQ

Frequently Asked Question

Install tools

Follow the instructions written on tiny-firware/README.md

Build instructions:

Immediately after cloning this repository make sure submoudules are up-to-date by executing the following command. All other commands expect this step completed first.

git submodule update --init --recursive

Should you find any issues while running any of the commands that follow please consult FAQ before reporting a bug.

Build and run emulator

make clean && make run-emulator

In case of needing special compiler flags for the SDL library it is possible to provide them in SDL_CFLAGS variable. For instance , if SDL was installed with brew on Mac OS X then the following command execution would force searching for header files at the right location.

make clean && make run-emulator SDL_CFLAGS=-I$(brew --prefix sdl2)/include/SDL2

However for the default brew installation in practice this should not be needed since the value of SDL_CFLAGS defaults to $(shell sdl2-config --cflags | sed 's/-D_THREAD_SAFE//g').

Build a bootloader

make bootloader # Your firmware is skybootloader-no-memory-protect.bin

Build a bootloader with memory protection enabled

Careful if you flash and run that bootloader on the device it will activate a memory protection that will close access to flash memory.

You won't be able to flash your device with an st-link again.

make bootloader-mem-protect # Your firmware is bootloader-memory-protected.bin

Build a firmware

make firmware  # Your firmware is tiny-firmware/skyfirmware.bin

Sign firmware

make sign # Your firmware is tiny-firmware/skyfirmware.bin

Combine bootloader and firmware

make full-firmware # this will create a full-firmware-no-mem-protect.bin file

Combine a memory protected bootloader and firmware

Careful if you flash and run that bootloader on the device it will activate a memory protection that will close access to flash memory.

You won't be able to flash your device with an st-link again.

make full-firmware-mem-protect # this will create a full-firmware-memory-protected.bin file 

Development guidelines

Code added in this repository should comply to development guidelines documented in Skycoin wiki.

The project has two branches: master and develop.

• develop is the default branch and will always have the latest code.
• master will always be equal to the current stable release on the website, and should correspond with the latest release tag.

Versioning policies

Firmware version scheme

The firmware defines a contract enforced upon all client libraries communicating with SkyWallet hardware devices. Firmware version expresses implemented contract version using a scheme based on semantic versioning. Individual components should be interpreted as follows :

• Major version number should be increased only if a new release introduces changes that are not backwards-compatible with respect to previous version
• Minor version number should be increased for releases adding incremental backwards-compatible changes to the firmware contract
• Patch version number should be increased for bug fix releases and similar changes keeping firmware contract unchanged

Firmware binary filename is skywallet-firmware-v$(VERSION_FIRMWARE).bin e.g. skywallet-firmware-v1.7.0.bin .

Bootloader version scheme

Bootloader versioning is independent and follows semantic versioning rules.

• Major version number indicates major changes in bootloader code
• Minor version number is used for progressive backwards-compatible changes
• Patch version number increased for bug fix releases

Bootloader binary filename is skywallet-bootloader-mem-protect-v$(VERSION_BOOTLOADER).bin if compiled with memory protection enabled, else skywallet-bootloader-no-memory-protect-v$(VERSION_BOOTLOADER).bin. For instance, skywallet-bootloader-mem-protect-v1.0.2.bin or skywallet-bootloader-no-memory-protect-v1.0.2.bin could be bootloader file names.

Versioning combined binary builds

The project releases production-ready binaries combining firmware and bootloader. A custom version scheme is used based on the rules that follow

• Bootloader version: Consecutive bootloader version identifier
• Firmware version: Consecutive firmware version identifier
• SoC identifier: With the Manufacturer and product identifiers reported in hidraw USB driver.
• Country Exit Code: to cope with i18n and locale specific features. At present only a value of en is supported for English according to ISO-639-1.

Version identifiers are strings including, in the same order, the numbers mentioned above separated by dots.

Combined binary filename is skywallet-full-mem-protect-$(COMBINED_VERSION).bin if compiled with memory protection enabled, else skywallet-full-no-mem-protect-$(COMBINED_VERSION).bin e.g. skywallet-full-no-mem-protect-102.170.1.1.bin and skywallet-full-mem-protect-102.107.1.1.bin.

Versioning libraries

In order to identify at first sight the features supported by a particular release of a client library, its major and minor version numbers should match the corresponding values of the version of the firmware they were built (tested) for. It is expected that the aforementioned library will be able to communicate to any firmware, as long as both versions (client and firmware) have the same major version number and firmware minor number is greater than the one of the library.

Running tests

The project includes a test suite. In order to run it just execute the following command

make clean && make test

Generating tests code coverage

To generate code coverage html report you need to have lcov available in your PATH, in a debian based system you can run apt install lcov, lcov can be available using brew on osx too, but in the most general case you can follow the the official install instructions. After having this tool you can run make check-coverage, if not errors found you can find the result in coverage/index.html.

Validate the TRNG

To be able to validate the device trng you need to install the following tools:

• dieharder (A testing and benchmarking tool for random number generators)
• ent (pseudorandom number sequence test)
• rng-tools (Check the randomness of data using FIPS 140-2 tests)

For example, in a debian based system you can run apt install dieharder ent rng-tools

In order to make the validation you need to build the firmware with ENABLE_GETENTROPY flag set o 1 and maybe you want to dissable button confirmation by seeting DISABLE_GETENTROPY_CONFIRM to 1, the following is an example:

make clean
make firmware ENABLE_GETENTROPY=1 DISABLE_GETENTROPY_CONFIRM=1

After this , connect a Skywallet device and just run the following command:

make check-trng

After running the tools some files are generated and need to be analyzed by a human. Some of they are easy(because have an Assessment column) at a first look like for example:

#=============================================================================#
#            dieharder version 3.31.1 Copyright 2003 Robert G. Brown          #
#=============================================================================#
   rng_name    |           filename             |rands/second|
        mt19937|                 stm32_rng_7.dat|  1.40e+08  |
#=============================================================================#
        test_name   |ntup| tsamples |psamples|  p-value |Assessment
#=============================================================================#
   diehard_birthdays|   0|       100|     100|0.73855343|  PASSED  
      diehard_operm5|   0|   1000000|     100|0.40846434|  PASSED  
  diehard_rank_32x32|   0|     40000|     100|0.87409050|  PASSED  
    diehard_rank_6x8|   0|    100000|     100|0.81487620|  PASSED  
   diehard_bitstream|   0|   2097152|     100|0.97506327|  PASSED  
        diehard_opso|   0|   2097152|     100|0.72414474|  PASSED  
        diehard_oqso|   0|   2097152|     100|0.14038586|  PASSED  
         diehard_dna|   0|   2097152|     100|0.29338685|  PASSED  
diehard_count_1s_str|   0|    256000|     100|0.08300743|  PASSED  
diehard_count_1s_byt|   0|    256000|     100|0.96142913|  PASSED  
 diehard_parking_lot|   0|     12000|     100|0.43595334|  PASSED  
    diehard_2dsphere|   2|      8000|     100|0.88771280|  PASSED  
    diehard_3dsphere|   3|      4000|     100|0.09017234|  PASSED  
     diehard_squeeze|   0|    100000|     100|0.56740432|  PASSED  
        diehard_sums|   0|       100|     100|0.00071665|   WEAK   
        diehard_runs|   0|    100000|     100|0.05569879|  PASSED  

But in general a bit of research should be done looking at the files content. This feature come mainly from https://github.com/trezor/rng-test, so any advice from this repo is good as well

Files description

Releases

Skycoin firmware releases

The skycoin firmware is composed of two parts: the bootloader and the firmware.

When plugging the device in, the bootloader runs first. Its only purpose it to check firmware's validity using Skycoin signature.

The firmware is expected to have a header with proper MAGIC number and three signature slots.

If the firmware does not have a valid signature in its header it is considered "not official". A warning will be displayed but the user can still skip it and use it anyway.

The "unofficial firmware warning", means that the firmware was not signed by Skycoin Foundation.

Skycoin firmware is open source and it is easy to fork or copy official repository and create concurrent firmware for the device. Skycoin Foundation however will not put its signature on it.

The Skycoin hardware will be shipped with an immutable bootloader written in a protected memory that is impossible to re-write.

The firmware however can evolve over time and some solutions were developed to update an existing firmware (see skycoin-hw-cli).

Supported languages

The supported languages are encoded in a masked 32 bits number:

• 0 English
• 1:31 Reserved

Full-Firmware and bootloader folder

The firmware and bootloader folders are here for development purpose. They are meant to be flashed with st-link on a STM32 device in which the memory protection was not enabled yet.

You can check here for instructions about how to burn a full firmware on a device.

Firmware folder

If you are a user of the skycoin electronic wallet and want to update your firmware. You can pick-up official and tested releases.

To update firmware the device must be in "bootloader mode". Press both buttons, unplug your device and plug it back in. Then you can use skycoin-cli firmwareUpdate message to update the firmware.

Update the version

0. If the master branch has commits that are not in develop (e.g. due to a hotfix applied to master), merge master into develop (and fix any build or test failures)
1. Switch to a new release branch named release-X.Y.Z for preparing the release.
2. Update tiny-firmware/VERSION and tiny-firmware/bootloader/VERSION with corresponding version numbers
3. Run make build to make sure that the code base is up to date
4. Update CHANGELOG.md: move the "unreleased" changes to the version and add the date.
5. Follow the steps in pre-release testing
6. Make a PR merging the release branch into master
7. Review the PR and merge it
8. Tag the master branch with the version number. Version tags start with v, e.g. v0.20.0. Sign the tag. If you have your GPG key in github, creating a release on the Github website will automatically tag the release. It can be tagged from the command line with git tag -as v0.20.0 $COMMIT_ID, but Github will not recognize it as a "release".
9. Tag the changeset of the protob submodule checkout with the same version number as above.
10. Release builds are created and uploaded by travis. To do it manually, checkout the master branch and follow the create release builds instructions.
11. Checkout develop branch and bump tiny-firmware/VERSION and tiny-firmware/bootloader/VERSION to next dev version number.

Pre-release testing

Once the candidate release build artifacts have been downloaded it is necessary to check once again that they behave according to specifications. The followinfg steps are aimed at ensuring this is the case. Execute

0. Flash the device with latest versions of bootloader and firmware
1. Ensure you have a recent version of Skycoin desktop software in one of the following ways

• build desktop wallet from source either following instructions from master branch or from develop branch
• download Skycoin wallet from official downloads page

0. Open desktop wallet
1. Recover a test wallet with nonzero balance from seed to confirm wallet loading works
2. Send coins to another wallet to confirm spending works
3. Check that transferred amounts reported in transaction history are correct
4. Add a PIN to the hardware wallet
5. Use the same recovery seed of the wallet configured in the Skywallet device and to load a wallet directly in desktop wallet
6. Send coins to another wallet again
7. Check transaction history once again
8. Wipe the wallet
9. Set up the hardware wallet with a random seed and write down the first address
10. Create a seed backup
11. Wipe the wallet and restore the seed. Check if the first address is equal to the one previously written
12. Repeat steps from the top but using combined bootloader + firmware image to flash the hardware wallet device.

Creating release builds

The following instruction creates a full release:

make release

Firmware version will be retrieved automatically from git, and bootloader version will be take from tiny-firmware/VERSION.

Responsible Disclosure

Security flaws in Skywallet source or infrastructure can be sent to security@skycoin.net. Bounties are available for accepted critical bug reports.

PGP Key for signing:

-----BEGIN PGP PUBLIC KEY BLOCK-----
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=5fwW
-----END PGP PUBLIC KEY BLOCK-----

Key ID: 0x5801631BD27C7874

The fingerprint for this key is:

pub   ed25519 2017-09-01 [SC] [expires: 2023-03-18]
      10A7 22B7 6F2F FE7B D238  0222 5801 631B D27C 7874
uid                      GZ-C SKYCOIN <token@protonmail.com>
sub   cv25519 2017-09-01 [E] [expires: 2023-03-18]

Keybase.io account: https://keybase.io/gzc