This is a generic Certificate Management Protocol (CMP) client library with a high-level API and associated CLI-based demo client, tests, and documentation.
The purpose of this software is to provide a high-level API on top of the detailed CMP (and CRMF) API of OpenSSL since version 3.0. It can be used with OpenSSL and with the intermediate CMP library CMPforOpenSSL providing the latest CMP features defined in CMP Updates .
The high-level API is on the one hand convenient to use for application programmers and on the other hand complete and flexible enough to cover the major certificate management use cases. The library supports developing CMP clients that adhere to the Lightweight CMP Profile (LCMPP) , which is geared towards simple and interoperable industrial use. The software also provides a command-line interface (CLI) that is handy for interactive exploration of using CMP in a PKI.
See the CHANGELOG.md file in the top-level directory.
The Generic CMP client API specification and CLI documentation are available in the doc folder.
The Doxygen documentation of the underlying Security Utilities library is available via a link in its README file.
This software should work with any flavor of Linux, including Cygwin, also on a virtual machine or the Windows Subsystem for Linux (WSL), and with MacOS X.
The following network and development tools are needed or recommended.
- Git (for getting the software, tested with versions 2.7.2, 2.11.0, 2.20, 2.30.2, 2.39.2)
- CMake (for using
CMakeLists.txt, tested with versions 3.18.4, 3.26.3, 3.27.7) - GNU make (tested with versions 3.81, 4.1, 4.2.1, 4.3)
- GNU C compiler (gcc, tested with versions 5.4.0, 7.3.0, 8.3.0, 10.0.1, 10.2.1) or clang (tested with version 14.0.3 and 17.0.3)
- wget (for running the demo, tested with versions 1.17, 1.18, 1.20, 1.21)
- Perl (for running the tests, tested with versions 5.30.3 and 5.32.1)
The following OSS components are used.
- OpenSSL development edition; supported versions: 3.0, 3.1, 3.2
- Security Utilities (libsecutils)
- CMPforOpenSSL,
a CMP+CRMF+HTTP extension to OpenSSL, needed when using OpenSSL 1.x
or if the latest CMP features not yet available in OpenSSL are required,
which can be indicated by setting the environment variable
USE_LIBCMP.
For instance, on a Debian or Ubuntu system the prerequisites may be installed simply as follows:
sudo apt install cmake libssl-dev libc-dev linux-libc-dev
while sudo apt install git make gcc wget usually is not needed as far as these tools are pre-installed.
You might need to set the variable OPENSSL_DIR first as described below, e.g.,
export OPENSSL_DIR=/usr/local
On a Mac OS X system the prerequisites may be installed by executing the following in a terminal:
brew install git make openssl cmake wget perl
When using gcc (instead of clang) and ccache:
brew install gcc ccache
For making sure that OpenSSL version 3 is installed:
brew uninstall --ignore-dependencies openssl@3
brew install openssl@3
brew --prefix openssl@3
As a sanity check you can execute in a shell on a Unix-like system:
git clone https://github.com/siemens/gencmpclient.git
cd genCMPClient
make -f OpenSSL_version.mk
This should output on the console something like
cc [...] OpenSSL_version.c -lcrypto -o OpenSSL_version
OpenSSL 3.0.8 7 Feb 2023 (0x30000080)
For accessing the code repositories on GitHub you may need an SSH client with suitable credentials or an HTTP proxy set up, for instance:
export https_proxy=http://proxy.example.com:8080
You can clone the git repository and its submodules with
git clone https://github.com/siemens/gencmpclient.git
cd genCMPClient
make -f Makefile_v1 get_submodules
This will fetch also the underlying CMPforOpenSSL extension to OpenSSL if needed and the Security Utilities (libsecutils) library.
For using the project as a git submodule, do for instance the following in the directory where you want to integrate it:
git submodule add git@github.com:siemens/gencmpclient.git
When you later want to update your local copy of all relevant repositories it is sufficient to invoke
make update
When switching to a certain commit or version, e.g.
git checkout v2.0
then also execute
git submodule update
make -f Makefile_v1 clean
to bring the submodules in a state consistent with that and remove any previous possibly outdated artifacts.
The generic CMP client (as well as its underlying libraries)
assumes that OpenSSL is already installed,
including the C header files needed for development
(as provided by, e.g., the Debian/Ubuntu package libssl-dev).
By default any OpenSSL installation available on the system is used.
Set the optional environment variable OPENSSL_DIR to specify the
absolute (or relative to ../) path of the OpenSSL installation to use.
This must point to the location in the file system from which include/openssl
is directly accessible with this relative path name.
In case its libraries are in a different location, set also OPENSSL_LIB.
Here are examples for Linux:
export OPENSSL_DIR=/usr/local
export OPENSSL_LIB=/lib/x86_64-linux-gnu
The value for OPENSSL_LIB may be obtained by
ldd `which openssl` | grep libcrypto.so | awk '{print $3}' | sed 's#/[^/]*$##'
On Mac OS X, these lines are suggested to add to ~/.zshrc
export LDFLAGS="-L$(brew --prefix openssl@3)/lib"
export CPPFLAGS="-I$(brew --prefix openssl@3)/include"
export OPENSSL_DIR=$(brew --prefix openssl@3)
export OPENSSL_LIB=$(brew --prefix openssl@3)/lib
After doing so, restart the terminal or copy&paste them there, too.
Define the environment variable USE_LIBCMP for using the latest CMP features
and fixes, which implies use of the intermediate library libcmp.
When using OpenSSL version 1.x, this is ensured automatically.
When using OpenSSL version 3.0 or 3.1 and USE_LIBCMP is not defined,
the new CMP features defined in CMP Updates and the Lightweight CMP Profile
will not be supported.
From the underlying Security Utilities library the following environment variables are inherited.
- When
SECUTILS_USE_ICVis set, configuration files are expected to be integrity protected with an Integrity Check Value (ICV), which may be produced usingutil/icvutil. - Use of the UTA library can be enabled by setting
SECUTILS_USE_UTA. - The TLS-related functions may be disabled by setting
SECUTILS_NO_TLS.
Since genCMPClient version 2, it is recommended to use CMake
to produce the Makefile, for instance as follows:
cmake .
When using CMake, cmake must be (re-)run
after setting or unsetting environment variables.
By default, CMake builds are in Release mode.
This may also be enforced by defining the environment variable NDEBUG.
For switching to Debug mode, use cmake with -DCMAKE_BUILD_TYPE=Debug.
The chosen mode is remembered in CMakeCache.txt.
For backward compatibility it is also possible to use instead of CMake
pre-defined Makefile_v1; to this end symlink it to Makefile:
ln -s Makefile_v1 Makefile
or use for instance make -f Makefile_v1.
By default, builds using Makefile_v1 are in Debug mode.
Release mode can be selected by defining the environment variable NDEBUG.
By default Makefile_v1 behaves as if
OPENSSL_DIR=/usr
was given, such that the OpenSSL headers will be searched for in /usr/include
and its shared objects in /usr/lib (or /usr/bin for Cygwin).
When using Makefile_v1, you may
specify via the environment variable OUT_DIR where the produced libraries
(e.g., libgencmp.so*, libcmp.so*, and libsecutils.so*) shall be placed.
It defaults to the base directory of the respective library.
If the environment variable BIN_DIR is not empty, the
the CLI application cmpClient will be built and placed in BIN_DIR.
If the variable is unset, . is used by default.
For all path variables, relative paths such as . are interpreted
relative to the directory of the genCMPClient module.
The CC environment variable may be set as needed; it defaults to gcc.
It is also possible to statically link with libcmp.a, using STATIC_LIBCMP.
For further details on optional environment variables,
see the Makefile_v1 and Makefile_src.
Build the software with
make
The result is in, for instance, ./libgencmp.so.2.0.
This also builds all required dependencies
(such as libsecutils/libsecutils.so.2.0 and cmpossl/libcmp.so.2.0)
and an application (./cmpClient) that is intended
for demonstration, test, and exploration purposes.
When getting the compiler error: 'openssl/openssl_backport.h' file not found
likely include/genericCMPClient_config.h is outdated
and contains #define USE_LIBCMP although the environment variable USE_LIBCMP
is not set. In such situations, make -f Makfile_v1 clean helps to reset it to a consistent state.
The software can be installed with, e.g.,
sudo make install
and uninstalled with
sudo make uninstall
The destination is /usr, unless specified otherwise by DESTDIR or ROOTFS.
make clean removes part of the artifacts, while
make clean_all removes everything produced by make and CMake.
This repository can build the following binary and source packages.
libgencmp- the shared librarylibgencmp-dev- development headers and documentationcmpclient- simple command-line application with its documentationlibgencmp*Source.tar.gz-- source tarball
The recommended way is to use CPack with the files produced by CMake as follows:
make deb
which requries the file utility.
Alternatively, Makefile_v1 may be used like this:
make -f Makefile_v1 deb
In this case, the resulting packages are placed in the parent directory (../),
and requires the following Debian packages:
debhelper(needed fordh)devscripts(needed fordebuild)libssl-dev
The Debian packages may be installed for instance as follows:
sudo dpkg -i libgencmp*deb cmpclient_*.deb
The CMP demo client is implemented in src/cmpClient.c
as part of the CLI.
For simple test invocations the Insta Certifier Demo CA server may be used, for instance as follows:
openssl ecparam -genkey -name prime256v1 -out test.key.pem
cmpClient -config "" -server pki.certificate.fi:8700/pkix/ \
-recipient "/C=FI/O=Insta Demo/CN=Insta Demo CA" \
-secret pass:insta -ref 3078 \
-cmd cr -newkey test.key.pem -subject "/CN=test" -certout test.cert.pem
openssl x509 -noout -text -in test.cert.pem
As the CMP client interacts via HTTP with an external CMP server, depending
on your network you may need to set the environment variable http_proxy.
A demo making use of all supported CMP commands can be executed with
make -f Makefile_v1 demo
The demo can be run using the online Insta Demo CA, which is the default, or using an included Docker instance of the EJBCA that can be launched locally:
make -f Makefile_v1 demo_EJBCA
or using the reference playground CA operated by Siemens over a test cloud CA:
make -f Makefile_v1 demo_CloudCA
Among others, successful execution should produce a new certificate at creds/operational.crt.
You can view this certificate for instance by executing
openssl x509 -noout -text -in creds/operational.crt
The Command-Line Interface (CLI) of the CMP client is implemented in
src/cmpClient.c.
It supports most of the features of the genCMPClient library.
The CLI use with the available options are documented in cmpClient.pod.
CLI-based tests using the external Insta Demo CA may be invoked using
make -f Makefile_v1 test_Insta
where the PROXY environment variable may be used to override the default in order to reach the Insta Demo CA.
For building the library (and optionally the CLI application) as part of other builds, it is recommended to use Debian packages or CMake.
Another possibility is to use Makefile_v1,
for instance as given in the example outer Makefile.mk.
For compiling applications using the library,
you will need to #include the header file genericCMPClient.h
and add the directories include and
libsecutils/include to your C headers path.
When the intermediate library libcmp is used, you need to
add also the directory cmpossl/include/cmp,
define the C macro USE_LIBCMP, and
make sure that any OpenSSL header files included have the same version
as the one used to build libcmp.
For linking you will need to
refer the linker to the CMP and Security Utilities libraries,
e.g., -lsecutils -lgencmp.
When the intermediate library libcmp is used, -lcmp is needed additionally.
Add the directories (e.g., with the linker option -L) where they can be found.
See also the environment variable OUT_DIR.
Consider using also linker options like -Wl,-rpath=.
for helping the Linux loader find the libraries at run time.
Also make sure that the OpenSSL libraries
(typically referred to via -lssl -lcrypto) are in your library path and
(the version of) the libraries found there by the linker match the header files found by the compiler.
All this is already done for the cmp client application.
This software including associated documentation is provided ‘as is’. Effort has been spent on quality assurance, but there are no guarantees.
This work is licensed under the terms of the Apache Software License 2.0. See the LICENSE.txt file in the top-level directory.
SPDX-License-Identifier: Apache-2.0
