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LibreSSL Portable itself. This includes the build scaffold and compatibility layer that builds portable LibreSSL from the OpenBSD source code. Pull requests or patches sent to are welcome.

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LibreSSL image

Official portable version of LibreSSL

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LibreSSL is a fork of OpenSSL 1.0.1g developed by the OpenBSD project. Our goal is to modernize the codebase, improve security, and apply best practice development processes from OpenBSD.

Compatibility with OpenSSL

LibreSSL provides much of the OpenSSL 1.1 API. The OpenSSL 3 API is not currently supported. Incompatibilities between the projects exist and are unavoidable since both evolve with different goals and priorities. Important incompatibilities will be addressed if possible and as long as they are not too detrimental to LibreSSL's goals of simplicity, security and sanity. We do not add new features, ciphers and API without a solid reason and require that new code be clean and of high quality.

LibreSSL is not ABI compatible with any release of OpenSSL, or necessarily earlier releases of LibreSSL. You will need to relink your programs to LibreSSL in order to use it, just as in moving between major versions of OpenSSL. LibreSSL's installed library version numbers are incremented to account for ABI and API changes.

Compatibility with other operating systems

While primarily developed on and taking advantage of APIs available on OpenBSD, the LibreSSL portable project attempts to provide working alternatives for other operating systems, and assists with improving OS-native implementations where possible.

At the time of this writing, LibreSSL is known to build and work on:

  • Linux (kernel 3.17 or later recommended)
  • FreeBSD (tested with 9.2 and later)
  • NetBSD (7.0 or later recommended)
  • HP-UX (11i)
  • Solaris 11 and later
  • Mac OS X (tested with 10.8 and later)
  • AIX (5.3 and later)
  • Emscripten (3.1.44 and later)

LibreSSL also supports the following Windows environments:

  • Microsoft Windows (Windows 7 / Windows Server 2008r2 or later, x86 and x64)
  • Wine (32-bit and 64-bit)
  • MinGW-w64, Cygwin, and Visual Studio

Official release tarballs are available at your friendly neighborhood OpenBSD mirror in directory LibreSSL, although we suggest that you use a mirror.

The LibreSSL portable build framework is also mirrored on GitHub.

Please report bugs either to the public mailing list, or to the GitHub issue tracker

Severe vulnerabilities or bugs requiring coordination with OpenSSL can be sent to the core team at

Building LibreSSL

Building from a Git checkout

If you have checked out this source using Git, or have downloaded a source tarball from GitHub, follow these initial steps to prepare the source tree for building. Note: Your build will fail if you do not follow these instructions! If you cannot follow these instructions or cannot meet these prerequisites, please download an official release distribution from instead. Using official releases is strongly advised if you are not a developer.

  1. Ensure that you have a bash shell. This is also required on Windows.
  2. Ensure that you have the following packages installed: automake, autoconf, git, libtool, perl.
  3. Run ./ to prepare the source tree for building.

Build steps using configure

Once you have the source tree prepared, run these commands to build and install:

./configure   # see ./configure --help for configuration options
make check    # runs builtin unit tests
make install  # set DESTDIR= to install to an alternate location

Alternatively, it is possible to run ./ to prepare a tarball.

Build steps using CMake

Once you have the source tree prepared, run these commands to build and install:

mkdir build
cd build
cmake ..
make test

For faster builds, you can use Ninja:

mkdir build-ninja
cd build-ninja
cmake -G"Ninja" ..
ninja test

Or another supported build system like Visual Studio:

mkdir build-vs2022
cd build-vs2022
cmake -G"Visual Studio 17 2022" ..

Additional CMake Options

Option Name Default Description
LIBRESSL_SKIP_INSTALL OFF allows skipping install() rules. Can be specified from command line using
LIBRESSL_APPS ON allows skipping application builds. Apps are required to run tests
LIBRESSL_TESTS ON allows skipping of tests. Tests are only available in static builds
BUILD_SHARED_LIBS OFF CMake option for building shared libraries.
ENABLE_ASM ON builds assembly optimized rules.
ENABLE_EXTRATESTS OFF Enable extra tests that may be unreliable on some platforms
ENABLE_NC OFF Enable installing TLS-enabled nc(1)
OPENSSLDIR Blank Set the default openssl directory. Can be specified from command line using

Build information for specific systems

HP-UX (11i)

Set the UNIX_STD environment variable to 2003 before running configure in order to build with the HP C/aC++ compiler. See the "standards(5)" man page for more details.

export UNIX_STD=2003

MinGW-w64 - Windows

LibreSSL builds against relatively recent versions of MinGW-w64, not to be confused with the original project. MinGW-w64 3.2 or later should work. See for more information.


When configuring LibreSSL for use with Emscripten, make sure to prepend emcmake to your cmake configuration command. Once configured, you can proceed with your usual cmake commands. For example:

emcmake cmake . -Bbuild
cmake --build build --config Release
ctest --test-dir build -C Release --output-on-failure

Using LibreSSL


Make a new folder in your project root (where your main CMakeLists.txt file is located) called CMake. Copy the FindLibreSSL.cmake file to that folder, and add the following line to your main CMakeLists.txt:


After your add_executable or add_library line in your CMakeLists.txt file add the following:

find_package(LibreSSL REQUIRED)

It will tell CMake to find LibreSSL and if found will let you use the following 3 interfaces in your CMakeLists.txt file:

  • LibreSSL::Crypto
  • LibreSSL::SSL
  • LibreSSL::TLS

If you for example want to use the LibreSSL TLS library in your test program, include it like so (SSL and Crypto are required by TLS and included automatically too):

target_link_libraries(test LibreSSL::TLS)

Full example:

cmake_minimum_required(VERSION 3.10.0)



add_executable(test Main.cpp)

find_package(LibreSSL REQUIRED)

target_link_libraries(test LibreSSL::TLS)


Following the guide in the sections above to compile LibreSSL using make and running sudo make install will install LibreSSL to the /usr/local/ folder, and will be found automatically by find_package. If your system installs it to another location, or you have placed them yourself in a different location, you can set the CMake variable LIBRESSL_ROOT_DIR to the correct path, to help CMake find the library.


Placing the library files in C:/Program Files/LibreSSL/lib and the include files in C:/Program Files/LibreSSL/include should let CMake find them automatically, but it is recommended that you use CMake-GUI to set the paths. It is more convenient as you can have the files in any folder you choose.