Ledger Secure SDK

Are you developing an application?

If you are developing an application, for a smooth and quick integration:

• See the developers’ documentation on the Developer Portal
• Go on Discord to chat with developer support and the developer community.

Introduction

This directory contains the SDK for Nano S, Nano X, Nano S+ and Stax applications development.

It is the unified version of the previous Nano S, Nano X, Nano S+ SDKs.

As the previous SDKs, this SDK is tightly linked to the Ledger Hardware Wallet OS: BOLOS.

Indeed, it allows to interact with syscalls and cxlib functions which are embedded in the OS.

Hence you should make sure to use the right SDK version matching your development device OS.

You can find below two possibilities to build against the right SDK version.

Using the docker image

The easiest way to build against last device OS is to use the docker image provided by ledger and accessible on ghcr.io.

The corresponding GIT repository can be found here. Please have a look at its README.md for information about its usage.

Using the SDK directly (advanced users)

Advanced users that have setup the Ledger development environment can use this repository to build apps.

But for that, they need to understand how OS and SDK compatibility are tracked. This is done with the API_LEVEL which is defined in Makefile.defines.

The API_LEVEL on master branch is kept as the reserved value 0.

For each released OS there is a corresponding tag in the format <Device>_<os_version>, e.g. NanoX_v2.1.0 for the release of the OS version v2.1.0 for Nano X device. While on this tag, if you look at the value of the API_LEVEL which is defined in Makefile.defines you will retrieve the OS API_LEVEL.

There are also API_LEVEL_<N> branches with API_LEVEL value set to N. Their purpose is to allow cherry-picks of bug fixes and improvements that are merged on master so that they are available when building the apps for the corresponding OS.

On these API_LEVEL_<N> branches, there are tags following the format v<N>.<minor>.<patch>, e.g. v1.1.0 where N is the API_LEVEL. These tags are used to generate the SDK_VERSION which is available at compile time and allows to track the SDK version used to build an app.

In short, to build an app for an OS, you should:

• Retrieve the OS API_LEVEL:
  • git checkout <device>_<os_version>
  • grep API_LEVEL Makefile.defines | head -n1
• Check out the API_LEVEL_<N> branch related to the OS API_LEVEL and make sure it is up to date:
  • git checkout API_LEVEL_<N>
  • git pull
  • The last commit should be tagged with the complete version of the SDK (v<N>.<x>.<y>)
• Build the app from your app folder:
  • make BOLOS_SDK=<path_to_sdk> TARGET=<target> where target is one of nanos, nanox, nanos2, stax, flex (nanos2 is used for Nano S+ device).

About API_LEVEL branches

This list the API_LEVEL branches with their purposed (corresponding OS) and state if they should still be patched or not (OS not “active” anymore). OS release candidates are only kept in the list when a corresponding OS release production might be released on the same API_LEVEL.

Name	Related OS	Active
1	nanox_2.1.0 nanos+_1.1.0	❌
2	only rc releases	❌
3	only rc releases	❌
4	only rc releases	❌
5	nanox_2.2.{0, 1, 2, 3} nanos+ 1.1.1	✔️
6	only rc releases	❌
7 / 7.1	only rc releases	❌
7.2	only rc releases (not compatible due to font update)	❌
8	stax_1.0.0	❌
9	only rc releases	❌
10	stax_1.1.0	❌
11	stax_1.2.0 stax_1.2.1	❌
12	nanox_2.3.0-rc2 nanos+_1.2.0-rc2	❌
13	stax_1.3.0	❌
14	only rc releases	❌
15	stax_1.4.0	✔️
16	europa_0.1.0-re1	❌
17	europa_0.1.0-re2	❌
18	europa_0.1.0-re3 flex_0.2.0-rc1 flex_0.2.0-rc2 nanox_2.3.0-rc5 nanos+_1.2.0-rc5	✔️
19	flex_1.0.0-rc1	✔️

Cherry-picking process:

• Fetch last changes from remote: git fetch --all

• Create a new branch to hold your cherry-picks: git checkout origin/API_LEVEL_X -b mybranch

• Cherry-pick your commits: git cherry-pick -x commit_sha1 (the -x is useful to track the original commit of a cherry-pick).

• Push your branch: git push origin mybranch

• Create a PR and indicate in it the PR where your cherry-pick where reviewed first.

Contributing

Pre-commit

This repository uses pre-commit to identify simple programming issues at the time of code check-in.

To enable pre-commit in your development environment:

1. Install pre-commit:

   pip install pre-commit

2. Add pre-commit hooks

   pre-commit install --hook-type pre-commit
   pre-commit install --hook-type commit-msg

Documentation

HTML documentation can be generated by typing:

• For Stax:

make doc TARGET=stax

• For Nano X or Nano S+:

make doc TARGET=nano

from root directory

The resulting documentation can be found in build/doc/html/index.html

If you have not already installed Doxygen, you can do it (on Linux-Ubuntu) with:

sudo apt-get install doxygen doxygen-doc graphviz