liboqs

liboqs

liboqs is an open source C library for quantum-safe cryptographic algorithms.

• liboqs
  • Overview
  • Status
    • Supported Algorithms
      • Key encapsulation mechanisms
      • Signature schemes
      • Stateful signature schemes
    • Limitations and Security
      • Platform limitations
      • Support limitations
  • Quickstart
    • Linux and Mac
    • Windows
    • Cross compilation
  • Documentation
  • Contributing
  • License
  • Acknowledgements

Overview

liboqs provides:

• a collection of open source implementations of quantum-safe key encapsulation mechanisms (KEMs) and digital signature algorithms; the full list can be found below
• a common API for these algorithms
• a test harness and benchmarking routines

liboqs is part of the Open Quantum Safe (OQS) project, which aims to develop and integrate into applications quantum-safe cryptography to facilitate deployment and testing in real world contexts. In particular, OQS provides prototype integrations of liboqs into protocols like TLS, X.509, and S/MIME, through our OpenSSL 3 Provider and we provide a variety of other post-quantum-enabled demos.

The OQS project is supported by the Post-Quantum Cryptography Alliance as part of the Linux Foundation. More information about the Open Quantum Safe project can be found at openquantumsafe.org.

Status

Supported Algorithms

The table below summarizes every algorithm family currently integrated into liboqs. For per-variant detail (including NIST level, constant-time status, formal verification, and available optimizations), see ALGORITHMS.md; for upstream sources and advisories, see the per-algorithm pages under docs/algorithms.

Names of algorithms standardized by NIST — ML-KEM, ML-DSA, and SLH-DSA — are stable; if NIST changes the implementation details, liboqs will adjust so that users are protected from such changes. All other names are subject to change. Which algorithms are built can be controlled via OQS_ALGS_ENABLED; by default, liboqs is built supporting every algorithm in the table, including experimental ones.

Key encapsulation mechanisms

Algorithm family	Standardization status	Primary implementation	Upstream maintenance	OQS tier
BIKE	Not selected by NIST	awslabs/bike-kem	TBD	Tier 3 (Community)
Classic McEliece	Under ISO consideration	PQClean/PQClean@1eacfda	No active maintenance	Tier 3 (Community)
FrodoKEM	Under ISO consideration	microsoft/PQCrypto-LWEKE@a2f9dec	Best effort	Tier 2 (Supported)
HQC	Selected by NIST for upcoming standardization	pqc-hqc/hqc@161cd4f	TBD	Tier 2 (Supported)
Kyber	Selected by NIST as basis for ML-KEM (FIPS 203)	pq-crystals/kyber@441c051	Actively maintained	Tier 3 (Community)
ML-KEM	Standardized by NIST	pq-code-package/mlkem-native@d1b2fe7	Actively maintained	Tier 1 (Core)
NTRU	Not selected by NIST, under standardization consideration by NTT	PQClean/PQClean@4c9e5a3	Actively maintained	Tier 3 (Community)
NTRU-Prime	Not selected by NIST	openssh/openssh-portable	Actively maintained	Tier 3 (Community)

Signature schemes

Algorithm family	Standardization status	Primary implementation	Upstream maintenance	OQS tier
CROSS	Under NIST consideration	CROSS-signature/CROSS-lib-oqs@ce9933c	Actively maintained	Tier 3 (Community)
Falcon	Selected by NIST for upcoming standardization	PQClean/PQClean@1eacfda	TBD	Tier 3 (Community)
MAYO	Under NIST consideration	PQCMayo/MAYO-C@74de637	Actively maintained	Tier 3 (Community)
ML-DSA	Standardized by NIST	pq-code-package/mldsa-native@834a90d	Actively maintained	Tier 2 (Supported)
MQOM	Under NIST consideration	mqom/mqom-v3@df26239	Actively maintained	Tier 3 (Community)
QR-UOV	Under NIST consideration	0rlych1kk4/round3@3965b56	TBD	Tier 3 (Community)
SDitH	Under NIST consideration	sdith/sdith@ce7adf0	TBD	Tier 3 (Community)
SLH-DSA	Standardized by NIST	pq-code-package/slhdsa-c@a0fc1ff	Best effort	Tier 3 (Community)
SNOVA	Under NIST consideration	PQCLAB-SNOVA/S@9b29c1e	Best effort	Tier 3 (Community)
SQIsign	Under NIST consideration	bhess/the-sqisign@7ec3841	Best effort	Tier 3 (Community)
UOV	Under NIST consideration	pqov/pqov@fac2ec1	Best effort	Tier 3 (Community)

Stateful signature schemes

Algorithm family	Standardization status	Primary implementation	Upstream maintenance	OQS tier
LMS	Standardized by IRTF, approved by NIST	cisco/hash-sigs	Best effort	Tier 2 (Supported)
XMSS	Standardized by IRTF, approved by NIST	XMSS/xmss-reference	Actively maintained	Tier 2 (Supported)

Limitations and Security

While at the time of this writing there are no vulnerabilities known in any of the quantum-safe algorithms used in this library, caution is advised when deploying quantum-safe algorithms as most of the algorithms and software have not been subject to the same degree of scrutiny as for currently deployed algorithms. Particular attention should be paid to guidance provided by the standards community, especially from the NIST Post-Quantum Cryptography Standardization project. As research advances, the supported algorithms may see rapid changes in their security, and may even prove insecure against both classical and quantum computers. Moreover, note that the sntrup761 is only included for interop testing.

liboqs does not intend to “pick winners”: algorithm support is informed by the NIST PQC standardization project. We strongly recommend that applications and protocols rely on the outcomes of this effort when deploying post-quantum cryptography.

We realize some parties may want to deploy quantum-safe cryptography prior to the conclusion of the NIST PQC standardization project. We strongly recommend such attempts make use of so-called hybrid cryptography, in which quantum-safe public-key algorithms are used alongside traditional public key algorithms (like RSA or elliptic curves) so that the solution is at least no less secure than existing traditional cryptography.

WE DO NOT CURRENTLY RECOMMEND RELYING ON THIS LIBRARY IN A PRODUCTION ENVIRONMENT OR TO PROTECT ANY SENSITIVE DATA. This library is meant to help with research and prototyping. While we make a best-effort approach to avoid security bugs, this library has not received the level of auditing and analysis that would be necessary to rely on it for high security use.

Please see SECURITY.md for details on how to report a vulnerability and the OQS vulnerability response process.

Platform limitations

In order to optimize support effort,

• not all algorithms are equally well supported on all platforms. In case of questions, it is first advised to review the documentation files for each algorithm.
• not all compilers are equally well supported. For example, at least v7.1.0 of the GNU compiler is required.

Support limitations

This project is not commercially supported. All guidelines and goals for liboqs are reflections of current practices, executed by a community of academic, part-time, and/or voluntary contributors on a best-effort basis and may change at any time. Any entity seeking more reliable commitments is strongly encouraged to join the OQS community and thus enhance the code and support that the community can provide.

Quickstart

Linux and Mac

1. Install dependencies:

   On Ubuntu:

    sudo apt install astyle cmake gcc ninja-build libssl-dev unzip xsltproc doxygen graphviz valgrind
    python3 -m venv .venv
    source .venv/bin/activate
    pip install --require-hashes -r requirements.txt
   

   On macOS, using a package manager of your choice (we’ve picked Homebrew):

    brew install cmake ninja openssl@3 wget doxygen graphviz astyle valgrind
    python3 -m venv .venv
    source .venv/bin/activate
    pip install --require-hashes -r requirements.txt
   

   Using Nix:

    nix develop
   

   Note that, if you want liboqs to use OpenSSL for various symmetric crypto algorithms (AES, SHA-2, etc.) then you must have OpenSSL 3.0 or newer installed.

2. Get the source:

    git clone -b main https://github.com/open-quantum-safe/liboqs.git
    cd liboqs
   

   and build:

    mkdir build && cd build
    cmake -GNinja ..
    ninja
   

Various cmake build options to customize the resultant artifacts are available and are documented in CONFIGURE.md. All supported options are also listed in the .CMake/alg-support.cmake file, and can be viewed by running cmake -LAH -N .. in the build directory.

The following instructions assume we are in build.

3. By default the main build result is lib/liboqs.a, a static library. If you want to build a shared/dynamic library, append -DBUILD_SHARED_LIBS=ON to the cmake -GNinja .. command above and the result will be lib/liboqs.so|dylib|dll. The public headers are located in the include directory. There are also a variety of programs built under the tests directory:

   • test_kem: Simple test harness for key encapsulation mechanisms
   • test_sig: Simple test harness for signature schemes
   • test_sig_stfl: Simple test harness for stateful signature schemes
   • test_kem_mem: Simple test harness for checking memory consumption of key encapsulation mechanisms
   • test_sig_mem: Simple test harness for checking memory consumption of signature schemes
   • kat_kem: Program that generates known answer test (KAT) values for key encapsulation mechanisms using the same procedure as the NIST submission requirements, for checking against submitted KAT values using tests/test_kat.py
   • kat_sig: Program that generates known answer test (KAT) values for signature schemes using the same procedure as the NIST submission requirements, for checking against submitted KAT values using tests/test_kat.py
   • kat_sig_stfl: Program for checking results against submitted KAT values using tests/test_kat.py
   • speed_kem: Benchmarking program for key encapsulation mechanisms; see ./speed_kem --help for usage instructions
   • speed_sig: Benchmarking program for signature mechanisms; see ./speed_sig --help for usage instructions
   • speed_sig_stfl: Benchmarking program for stateful signature mechanisms; see ./speed_sig_stfl --help for usage instructions
   • example_kem: Minimal runnable example showing the usage of the KEM API
   • example_sig: Minimal runnable example showing the usage of the signature API
   • example_sig_stfl: Minimal runnable example showing the usage of the stateful signature API
   • test_aes, test_sha3: Simple test harnesses for crypto sub-components
   • test_portability: Simple test harnesses for checking cross-CPU code portability; requires presence of qemu; proper operation validated only on Ubuntu

   The complete test suite can be run using

    ninja run_tests
   

4. To generate HTML documentation of the API, run:

    ninja gen_docs
   

   Then open docs/html/index.html in your web browser.

5. ninja install can be run to install the built library and include files to a location of choice, which can be specified by passing the -DCMAKE_INSTALL_PREFIX=<dir> option to cmake at configure time. Alternatively, ninja package can be run to create an install package.

6. ninja uninstall can be run to remove all installation files.

Windows

Binaries can be generated using Visual Studio 2019 with the CMake Tools extension installed. The same options as explained above for Linux/macOS can be used and build artifacts are generated in the specified build folders.

If you want to create Visual Studio build files, e.g., if not using ninja, be sure to not pass the parameter -GNinja to the cmake command as exemplified above. You can then build all components using msbuild, e.g. as follows: msbuild ALL_BUILD.vcxproj and install all artifacts e.g. using this command msbuild INSTALL.vcxproj.

Cross compilation

You can cross compile liboqs for various platforms. Detailed information is available in the Wiki.

Documentation

More detailed information on building, optional build parameters, example applications, coding conventions and more can be found in the wiki.

Contributing

Contributions that meet the acceptance criteria are gratefully welcomed. See our Contributing Guide for more details.

License

liboqs is licensed under the MIT License; see LICENSE.txt for details.

liboqs includes some third party libraries or modules that are licensed differently; the corresponding subfolder contains the license that applies in that case. In particular:

• .CMake/CMakeDependentOption.cmake: BSD 3-Clause License
• src/common/common.c: includes portions which are Apache License v2.0
• src/common/crypto/aes/aes_c.c: public domain or any OSI-approved license
• src/common/crypto/aes/aes*_ni.c: public domain
• src/common/crypto/sha2/sha2_c.c: public domain
• src/common/crypto/sha3/xkcp_low : CC0 (public domain), except brg_endian.h and KeccakP-1600-AVX2.s
• src/common/crypto/sha3/xkcp_low/.../brg_endian.h : BSD 3-Clause License
• src/common/crypto/sha3/xkcp_low/.../KeccakP-1600-AVX2.s : BSD-like CRYPTOGAMS license
• src/common/rand/rand_nist.c: See file
• src/kem/bike/additional: Apache License v2.0
• src/kem/classic_mceliece/pqclean_*: public domain
• src/kem/kyber/pqcrystals-*: public domain (CC0) or Apache License v2.0
• src/kem/kyber/pqclean_*: public domain (CC0), and public domain (CC0) or Apache License v2.0, and public domain (CC0) or MIT, and MIT
• src/kem/kyber/libjade_* public domain (CC0) or Apache License v2.
• src/kem/ml_kem/mlkem-native_*: MIT or Apache License v2.0 or ISC License
• src/kem/ntru/pqclean_*: public domain (CC0)
• src/kem/ntruprime/sntrup761_openssh: public domain
• src/sig/falcon/pqclean_*_aarch64 : Apache License v2.0
• src/sig/mayo/*: Apache License v2.0
• src/sig/ml_dsa/pqcrystals-*: public domain (CC0) or Apache License v2.0

Acknowledgements

The OQS project is supported by the Post-Quantum Cryptography Alliance as part of the Linux Foundation.

The OQS project was founded by Douglas Stebila and Michele Mosca at the University of Waterloo. Contributors to liboqs include individual contributors, academics and researchers, and various companies, including Amazon Web Services, Cisco Systems, evolutionQ, IBM Research, Microsoft Research, SandboxAQ, and softwareQ.

Financial support for the development of Open Quantum Safe has been provided by Amazon Web Services, the Canadian Centre for Cyber Security, Cisco, the Unitary Fund, the NGI Assure Fund, and VeriSign Inc.

Research projects which developed specific components of OQS have been supported by various research grants, including funding from the Natural Sciences and Engineering Research Council of Canada (NSERC); see the source papers for funding acknowledgments.