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


liboqs provides:

  • a collection of open source implementations of quantum-safe key encapsulation mechanism (KEM) 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 led by Douglas Stebila and Michele Mosca, 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 TLS and SSH, through OpenSSL and OpenSSH.

More information on OQS can be found here and in the associated whitepapers.


Supported Algorithms

Details on each supported algorithm can be found in the docs/algorithms folder.

Key encapsulation mechanisms

  • Classic McEliece: Classic-McEliece-348864†, Classic-McEliece-348864f†, Classic-McEliece-460896†, Classic-McEliece-460896f†, Classic-McEliece-6688128†, Classic-McEliece-6688128f†, Classic-McEliece-6960119†, Classic-McEliece-6960119f†, Classic-McEliece-8192128†, Classic-McEliece-8192128f†
  • FrodoKEM: FrodoKEM-640-AES, FrodoKEM-640-SHAKE, FrodoKEM-976-AES, FrodoKEM-976-SHAKE, FrodoKEM-1344-AES, FrodoKEM-1344-SHAKE
  • HQC: HQC-128-1-CCA2, HQC-192-1-CCA2, HQC-192-2-CCA2, HQC-256-1-CCA2†, HQC-256-2-CCA2†, HQC-256-3-CCA2†
  • Kyber: Kyber512, Kyber768, Kyber1024, Kyber512-90s, Kyber768-90s, Kyber1024-90s
  • NewHope: NewHope-512-CCA, NewHope-1024-CCA
  • NTRU: NTRU-HPS-2048-509, NTRU-HPS-2048-677, NTRU-HPS-4096-821, NTRU-HRSS-701
  • SABER: LightSaber-KEM, Saber-KEM, FireSaber-KEM
  • SIKE: SIDH-p434, SIDH-p503, SIDH-p610, SIDH-p751, SIKE-p434, SIKE-p503, SIKE-p610, SIKE-p751, SIDH-p434-compressed, SIDH-p503-compressed, SIDH-p610-compressed, SIDH-p751-compressed, SIKE-p434-compressed, SIKE-p503-compressed, SIKE-p610-compressed, SIKE-p751-compressed
  • ThreeBears: BabyBearEphem, BabyBear, MamaBearEphem, MamaBear, PapaBearEphem, PapaBear

Signature schemes

  • Dilithium: Dilithium2, Dilithium3, Dilithium4
  • Falcon: Falcon-512, Falcon-1024
  • MQDSS: MQDSS-31-48, MQDSS-31-64
  • Picnic: Picnic-L1-FS, Picnic-L1-UR, Picnic-L1-full, Picnic-L3-FS, Picnic-L3-UR, Picnic-L3-full, Picnic-L5-FS, Picnic-L5-UR, Picnic-L5-full, Picnic3-L1, Picnic3-L3, Picnic3-L5
  • qTesla: qTesla-p-I, qTesla-p-III
  • Rainbow: Rainbow-Ia-Classic, Rainbow-Ia-Cyclic, Rainbow-Ia-Cyclic-Compressed, Rainbow-IIIc-Classic†, Rainbow-IIIc-Cyclic†, Rainbow-IIIc-Cyclic-Compressed†, Rainbow-Vc-Classic†, Rainbow-Vc-Cyclic†, Rainbow-Vc-Cyclic-Compressed†
  • SPHINCS+-Haraka: SPHINCS+-Haraka-128f-robust, SPHINCS+-Haraka-128f-simple, SPHINCS+-Haraka-128s-robust, SPHINCS+-Haraka-128s-simple, SPHINCS+-Haraka-192f-robust, SPHINCS+-Haraka-192f-simple, SPHINCS+-Haraka-192s-robust, SPHINCS+-Haraka-192s-simple, SPHINCS+-Haraka-256f-robust, SPHINCS+-Haraka-256f-simple, SPHINCS+-Haraka-256s-robust, SPHINCS+-Haraka-256s-simple
  • SPHINCS+-SHA256: SPHINCS+-SHA256-128f-robust, SPHINCS+-SHA256-128f-simple, SPHINCS+-SHA256-128s-robust, SPHINCS+-SHA256-128s-simple, SPHINCS+-SHA256-192f-robust, SPHINCS+-SHA256-192f-simple, SPHINCS+-SHA256-192s-robust, SPHINCS+-SHA256-192s-simple, SPHINCS+-SHA256-256f-robust, SPHINCS+-SHA256-256f-simple, SPHINCS+-SHA256-256s-robust, SPHINCS+-SHA256-256s-simple
  • SPHINCS+-SHAKE256: SPHINCS+-SHAKE256-128f-robust, SPHINCS+-SHAKE256-128f-simple, SPHINCS+-SHAKE256-128s-robust, SPHINCS+-SHAKE256-128s-simple, SPHINCS+-SHAKE256-192f-robust, SPHINCS+-SHAKE256-192f-simple, SPHINCS+-SHAKE256-192s-robust, SPHINCS+-SHAKE256-192s-simple, SPHINCS+-SHAKE256-256f-robust, SPHINCS+-SHAKE256-256f-simple, SPHINCS+-SHAKE256-256s-robust, SPHINCS+-SHAKE256-256s-simple

Note that algorithms marked with a dagger (†) have large stack usage and may cause failures when run on threads or in constrained environments.

Limitations and Security

As research advances, the supported algorithms may see rapid changes in their security, and may even prove insecure against both classical and quantum computers.

liboqs does not intend to "pick winners": algorithm support is informed by the NIST Post-Quantum Cryptography Standardization project. We strongly recommend that applications and protocols rely on the outcomes of ths effort when deploying post-quantum cryptography.

We realize some parties may want to deploy quantum-safe cryptography prior to the conclusion of the NIST 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.



  1. Install dependencies:

    On Ubuntu:

      sudo apt install cmake gcc ninja-build libssl-dev python3-pytest python3-pytest-xdist unzip xsltproc doxygen graphviz

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

     brew install cmake ninja openssl@1.1 wget doxygen graphviz
     pip3 install pytest pytest-xdist

    Note that, if you want liboqs to use OpenSSL for various symmetric crypto algorithms (AES, SHA-2, etc.) then you must have OpenSSL version 1.1.1 or higher.

  2. Get the source:

     git clone -b master
     cd liboqs

    and build:

     mkdir build && cd build
     cmake -GNinja ..

Various options can be passed to cmake to customize the build. Some of them include:

  • -DOQS_USE_OPENSSL=<val>: <val> can be ON or OFF; when ON, liboqs uses OpenSSL's AES, SHA-2, and SHA-3 implementations.
  • -DBUILD_SHARED_LIBS=<val>: <val> can be ON or OFF; when ON, CMake generates instructions for building a shared library, otherwise it generates instructions for building a static library.
  • -DOPENSSL_ROOT_DIR=<dir>: <dir> specifies the directory in which CMake will look for OpenSSL.

All supported options are listed in the .CMake/alg-support.cmake file, and can be viewed by running cmake -LAH .. in the build directory. They are also listed and explained in the wiki.

The following instructions assume we are in build.

  1. The main build result is lib/liboqs.a, a static library. 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 key 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/
    • 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/
    • 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
    • example_kem: Minimal runnable example showing the usage of the KEM API
    • example_sig: Minimal runnable example showing the usage of the signature API
    • test_aes, test_sha3: Simple test harnesses for crypto sub-components

    The test suite can be run using

     ninja run_tests
  2. To generate HTML documentation of the API, run:

     ninja gen_docs

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

  3. Finally, 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.


Binaries can be generated using Visual Studio 2019 with the CMake Tools extension installed.

Cross compilation

You can cross compile liboqs for various platform by supplying CMake with an appropriate toolchain file.

For example, to cross compile for a Raspberry Pi from Ubuntu Bionic:

apt install gcc-8-arm-linux-gnueabihf
mkdir build && cd build
cmake -GNinja -DCMAKE_TOOLCHAIN_FILE=../.CMake/toolchain_rasppi.cmake -DOQS_USE_OPENSSL=OFF ..

Or to compile for Windows AMD64 from Ubuntu Bionic:

apt install gcc-mingw-w64
mkdir build && cd build
cmake -GNinja -DCMAKE_TOOLCHAIN_FILE=../.CMake/toolchain_windows-amd64.cmake -DOQS_USE_CPU_EXTENSIONS=OFF ..


Further information can be found in the wiki.


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


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/fips202.c: public domain
  • src/common/crypto/sha3/keccak4x: CC0 (public domain), except brg_endian.h
  • src/kem/bike/additional: Apache License v2.0
  • src/kem/classic_mceliece/pqclean_*: public domain
  • src/kem/kyber/pqclean_*: public domain
  • src/kem/newhope/pqclean_*: public domain
  • src/kem/ntru/pqclean_*: public domain
  • src/kem/saber/pqclean_*: public domain
  • src/sig/dilithium/pqclean_*: public domain
  • src/sig/mqdss/pqclean_*: CC0 (public domain)
  • src/sig/picnic/external/sha3: CC0 (public domain)
  • src/sig/rainbow/pqclean_*: CC0 (public domain)
  • src/sig/sphincs/pqclean_*: CC0 (public domain)


Various companies, including Amazon Web Services, Cisco Systems, evolutionQ, IBM Research, and Microsoft Research have dedicated programmer time to contribute source code to OQS. Various people have contributed source code to liboqs.

Financial support for the development of Open Quantum Safe has been provided by Amazon Web Services and the Tutte Institute for Mathematics and Computing. 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.

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