Key block library and tools for ANSI X9.143, ASC X9 TR-31 and ISO 20038

This project began as an implementation of the ASC X9 TR-31 standard and has since grown to include the ANSI X9.143 standard which supersedes it, and the ISO 20038 standard which extends it. However, this project continues to refer to the library as TR-31 and prefixes the API, data types and command line tool with tr31, while mostly avoiding that naming when refering to key blocks and data associated with key blocks. Given that most uses of these standards involve dedicated security hardware, this implementation is mostly for validation and debugging purposes.

If you wish to use this library for a project that is not compatible with the terms of the LGPL v2.1 license, please contact the author for alternative licensing options.

Features

Currently this project implements parsing/decryption and encoding/encryption of key block format versions A, B, C, D and E. Various helper functions are also available to stringify key block header attributes. The functionality is available as a library as well as a command line tool.

Installation

• For Ubuntu 20.04 LTS (Focal), 22.04 LTS (Jammy), or 24.04 LTS (Noble) install the appropriate release package
• For Fedora 39 or Fedora 40, install the appropriate release package
• For Gentoo, use the OpenEMV overlay, set the keywords and useflags as needed, and install using emerge --verbose --ask tr31
• For MacOS with Homebrew, use the OpenEMV tap and install using brew install openemv/tap/tr31
• For Windows, use MSYS2 and follow the build instructions below
• For other platforms, architectures or configurations, follow the build instructions below

Dependencies

• C11 compiler such as GCC or Clang
• CMake
• TR-31 library requires MbedTLS (preferred), or OpenSSL
• tr31-tool will be built by default and requires argp (either via Glibc, a system-provided standalone or a downloaded implementation; see MacOS / Windows). Use the BUILD_TR31_TOOL option to prevent TR-31 tool from being built and avoid the dependency on argp.
• Doxygen can optionally be used to generate API documentation if it is available; see Documentation
• bash-completion can optionally be used to generate bash completion for tr31-tool

This project also makes use of sub-projects that can either be provided as git submodules using git clone --recurse-submodules, or provided as CMake targets by a parent project:

• OpenEMV common crypto abstraction

Build

This project uses CMake and can be built using the usual CMake steps.

To generate the build system in the build directory, use:

cmake -B build

To build the project, use:

cmake --build build

Consult the CMake documentation regarding additional options that can be specified in the above steps.

Testing

The tests can be run using the test target of the generated build system.

To run the tests using CMake, do:

cmake --build build --target test

Alternatively, ctest can be used directly which also allows actions such as MemCheck to be performed or the number of jobs to be set, for example:

ctest --test-dir build -T MemCheck -j 10

Documentation

If Doxygen was found by CMake, then HTML documentation can be generated using the docs target of the generated build system.

To generate the documentation using CMake, do:

cmake --build build --target docs

Alternatively, the BUILD_DOCS option can be specified when generating the build system by adding -DBUILD_DOCS=YES.

Packaging

If the required packaging tools were found (dpkg and/or rpmbuild on Linux) by CMake, packages can be created using the package target of the generated build system.

To generate the packages using CMake, do:

cmake --build build --target package

Alternatively, cpack can be used directly from within the build directory (build in the above Build steps).

This is an example of how monolithic release packages can be built from scratch on Ubuntu or Fedora:

rm -Rf build &&
cmake -B build -DCMAKE_BUILD_TYPE="RelWithDebInfo" -DCMAKE_INSTALL_PREFIX=/usr -DBUILD_SHARED_LIBS=YES -DBUILD_DOCS=YES -DCPACK_COMPONENTS_GROUPING=ALL_COMPONENTS_IN_ONE &&
cmake --build build &&
cmake --build build --target package

MacOS / Windows

On platforms such as MacOS or Windows where static linking is desirable and dependencies such as MbedTLS or argp may be unavailable, the FETCH_MBEDTLS and FETCH_ARGP options can be specified when generating the build system.

In addition, MacOS universal binaries can be built by specifying the desired architectures using the CMAKE_OSX_ARCHITECTURES option.

This is an example of how a self-contained, static, universal binary can be built from scratch for MacOS:

rm -Rf build &&
cmake -B build -DCMAKE_OSX_ARCHITECTURES="x86_64;arm64" -DCMAKE_BUILD_TYPE="RelWithDebInfo" -DFETCH_MBEDTLS=YES -DFETCH_ARGP=YES &&
cmake --build build

Usage

The available command line options of the tr31-tool application can be displayed using:

tr31-tool --help

To decode a key block, use the --import option. For example:

tr31-tool --import B0128B1TX00N0300KS18FFFF00A0200001E00000KC0C000169E3KP0C00ECAD626F9F1A826814AA066D86C8C18BD0E14033E1EBEC75BEDF586E6E325F3AA8C0E5

To decrypt a key block, add the --kbpk option to specify the key block protection key to be used for decryption. For example:

tr31-tool --import B0128B1TX00N0300KS18FFFF00A0200001E00000KC0C000169E3KP0C00ECAD626F9F1A826814AA066D86C8C18BD0E14033E1EBEC75BEDF586E6E325F3AA8C0E5 --kbpk AB2E09DB3EF0BA71E0CE6CD755C23A3B

To encode/encrypt a key block, use the --export option to specify the key to be wrapped/encrypted. The key block attributes can be specified using either a combination of the --export-format-version B, --export-key-algorithm and --export-template options, or using the --export-header option. For example:

tr31-tool --kbpk AB2E09DB3EF0BA71E0CE6CD755C23A3B --export BF82DAC6A33DF92CE66E15B70E5DCEB6 --export-header B0000B1TX00N0200KS18FFFF00A0200001E00000KC0C000169E3

Individual optional blocks can also be added when exporting a key block by using the various --export-opt-block-XX functions, where XX is the optional block identifier. For example:

tr31-tool --kbpk AB2E09DB3EF0BA71E0CE6CD755C23A3B --export BF82DAC6A33DF92CE66E15B70E5DCEB6 --export-header B0000B1TX00N0000 --export-opt-block-KS FFFF00A0200001E00000 --export-opt-block-KC

To decode non-standard key blocks, use the --import-no-strict-validation option to disable strict validation during key block import. For example:

tr31-tool --import D014410A100N0200101CIBMC01140123456789ABCDEFPB04012345678901234567890123456789012345678901234567890123456789012345678901234567890123456789012345 --import-no-strict-validation

Roadmap

• Implement key block translation
• Implement key block component combination
• Add support for vcpkg
• Test on various ARM architectures

License

Copyright 2020-2024 Leon Lynch.

This project is licensed under the terms of the LGPL v2.1 license. See LICENSE file.