Smartcard Support Packages

This directory contains external buildroot packages for smartcard hardware wallet support in SeedSigner.

Packages Included

python-pyscard v2.3.1

Description: Python wrapper for PC/SC (Personal Computer/Smart Card) API
Purpose: Low-level smartcard communication interface
Source: https://github.com/LudovicRousseau/pyscard
License: LGPL
Build System: setuptools

Dependencies:

host-swig (build-time, for C wrapper generation)
PC/SC middleware (runtime, provided by pcscd)

Files:

python-pyscard/Config.in - Buildroot configuration option
python-pyscard/python-pyscard.mk - Buildroot package makefile
python-pyscard/python-pyscard.hash - Package integrity verification
python-pyscard/0001-drop-swig-from-pyproject.patch - Remove swig from Python deps
python-pyscard/0002-skip-swig-check.patch - Skip swig presence check

Patches Explained:

The pyscard package requires SWIG to generate Python-C bindings. However, it incorrectly tries to install swig as a Python package (which doesn’t exist). The patches fix this:

0001-drop-swig-from-pyproject.patch: Removes swig from pyproject.toml build requirements since buildroot provides host-swig as a native tool
0002-skip-swig-check.patch: Skips the runtime check for swig on PATH, trusting buildroot’s dependency management

python-pysatochip v0.6a

Description: Python API for Satochip hardware wallet devices
Purpose: High-level interface for Satochip, Satodime, and Seedkeeper devices
Source: https://github.com/3rdIteration/pysatochip
License: LGPL
Build System: setuptools

Single version on all platforms. Every hardware platform (Luckfox/uClibc, Raspberry Pi and La Frite/glibc) pins the same pysatochip version. Toolchain compatibility is handled inside the package (e.g. certificate_validator.py falls back from OpenSSL to pycryptodomex automatically) — never via divergent per-toolchain version pins in the .mk. The same principle applies to all external packages (see python-pgpy). Bumping a version requires a full image rebuild on every platform.

Dependencies:

python-pyscard (runtime, for smartcard communication)

Files:

python-pysatochip/Config.in - Buildroot configuration option
python-pysatochip/python-pysatochip.mk - Buildroot package makefile
python-pysatochip/python-pysatochip.hash - Package integrity verification

How External Packages Work

Directory Structure

External packages in buildroot follow this structure:

external-packages/
├── python-pyscard/
│   ├── Config.in              # Menu configuration
│   ├── python-pyscard.mk      # Build instructions
│   ├── python-pyscard.hash    # SHA256 checksum
│   └── *.patch                # Source code patches
└── python-pysatochip/
    ├── Config.in
    ├── python-pysatochip.mk
    └── python-pysatochip.hash

Integration with Build System

1. Package Discovery:

Buildroot discovers external packages through the BR2_EXTERNAL_SEEDSIGNER_PATH variable which points to this directory. The build scripts add menu entries:

menu "SeedSigner"
    source "$BR2_EXTERNAL_SEEDSIGNER_PATH/package/python-pyscard/Config.in"
    source "$BR2_EXTERNAL_SEEDSIGNER_PATH/package/python-pysatochip/Config.in"
endmenu

2. Configuration:

In buildroot/configs/luckfox_pico_defconfig:

BR2_PACKAGE_PYTHON_PYSCARD=y
BR2_PACKAGE_PYTHON_PYSATOCHIP=y

3. Build Process:

When enabled, buildroot:

Downloads source from GitHub
Verifies SHA256 hash
Applies patches (if any)
Builds using setuptools
Installs to target rootfs

Package Makefiles

The .mk files define how to build each package:

python-pyscard.mk:

PYTHON_PYSCARD_VERSION = 2.3.1
PYTHON_PYSCARD_SITE = $(call github,LudovicRousseau,pyscard,$(PYTHON_PYSCARD_VERSION))
PYTHON_PYSCARD_SETUP_TYPE = setuptools
PYTHON_PYSCARD_LICENSE = LGPL
PYTHON_PYSCARD_DEPENDENCIES += host-swig
PYTHON_PYSCARD_ENV += SWIG="$(HOST_DIR)/bin/swig"

$(eval $(python-package))

python-pysatochip.mk:

PYTHON_PYSATOCHIP_VERSION = 0.5-alpha
PYTHON_PYSATOCHIP_SITE = $(call github,3rdIteration,pysatochip,$(PYTHON_PYSATOCHIP_VERSION))
PYTHON_PYSATOCHIP_SETUP_TYPE = setuptools
PYTHON_PYSATOCHIP_LICENSE = LGPL

$(eval $(python-package))

Installation Verification

After a successful build, verify the packages are installed:

Check pyscard:

# On the device
python3 -c "import smartcard; print(smartcard.__version__)"
python3 -c "from smartcard.System import readers; print(len(readers()))"

Check pysatochip:

# On the device
python3 -c "import pysatochip; print('pysatochip loaded successfully')"

Verify file locations:

# On the device
ls -la /usr/lib/python3.*/site-packages/smartcard/
ls -la /usr/lib/python3.*/site-packages/pysatochip/

Troubleshooting

Build Failures

Error: “swig not found”

Cause: host-swig dependency missing
Solution: Ensure PYTHON_PYSCARD_DEPENDENCIES += host-swig is in .mk file

Error: “SHA256 mismatch”

Cause: Source tarball doesn’t match expected hash
Solution: Update hash in .hash file or verify source URL

Error: “Cannot import smartcard”

Cause: Package not built or not installed to rootfs
Solution: Check build logs, verify BR2_PACKAGE_PYTHON_PYSCARD=y in defconfig

Runtime Issues

Error: “No readers found”

Cause: PC/SC daemon (pcscd) not running or no smartcard reader connected
Solution: Ensure hardware is connected and pcscd service is running

Error: “SCardEstablishContext failed”

Cause: PC/SC middleware not available
Solution: Install and start pcscd service (may need additional packages)

Adding New External Packages

To add a new external package:

Create package directory:

mkdir buildroot/external-packages/python-mypackage

Create Config.in:

config BR2_PACKAGE_PYTHON_MYPACKAGE
    bool "python-mypackage"
    help
      Description of package
      https://github.com/user/repo

Create package.mk:

PYTHON_MYPACKAGE_VERSION = 1.0.0
PYTHON_MYPACKAGE_SITE = $(call github,user,repo,$(PYTHON_MYPACKAGE_VERSION))
PYTHON_MYPACKAGE_SETUP_TYPE = setuptools
PYTHON_MYPACKAGE_LICENSE = MIT
   
$(eval $(python-package))

Create package.hash:

# From GitHub release or PyPI
sha256 abc123... python-mypackage-1.0.0.tar.gz

Add to defconfig:
```
BR2_PACKAGE_PYTHON_MYPACKAGE=y
```

Add to build script menus:

source "$BR2_EXTERNAL_SEEDSIGNER_PATH/package/python-mypackage/Config.in"

References

Buildroot Manual: https://buildroot.org/downloads/manual/manual.html
Python Package Infrastructure: https://buildroot.org/downloads/manual/manual.html#_infrastructure_for_python_packages
BR2_EXTERNAL: https://buildroot.org/downloads/manual/manual.html#outside-br-custom
pyscard Documentation: https://pyscard.sourceforge.io/
Satochip Documentation: https://satochip.io/

License

These external packages are separately licensed:

python-pyscard: LGPL (see package source)
python-pysatochip: LGPL (see package source)

The integration files (Config.in, .mk files, patches) are part of the seedsigner-luckfox-pico repository.