This repository contains code to enable quantum-safe cryptography (QSC) in a standard OpenSSL (3.x) distribution by way of implementing a single shared library, the OQS provider.

This repository has been derived from the OQS-OpenSSL3 branch in https://github.com/open-quantum-safe/openssl creating a provider that can be built outside the OpenSSL source tree.

Currently this provider fully enables quantum-safe cryptography for KEM key establishment in TLS1.3 including management of such keys via the OpenSSL (3.0) provider interface and hybrid KEM schemes. Also, QSC signatures including CMS functionality are available via the OpenSSL EVP interface. Key persistence is provided via the encode/decode mechanism and X.509 data structures. Also available is support for TLS1.3 signature functionality via the OpenSSL3 fetchable signature algorithm feature.

This implementation makes available the following quantum safe algorithms:

• BIKE: bikel1, bikel3, bikel5
• CRYSTALS-Kyber: kyber512, kyber768, kyber1024, kyber90s512, kyber90s768, kyber90s1024
• FrodoKEM: frodo640aes, frodo640shake, frodo976aes, frodo976shake, frodo1344aes, frodo1344shake
• HQC: hqc128, hqc192, hqc256†
• CRYSTALS-Dilithium:dilithium2*, dilithium3*, dilithium5*, dilithium2_aes*, dilithium3_aes*, dilithium5_aes*
• Falcon:falcon512*, falcon1024*
• SPHINCS-Haraka:sphincsharaka128frobust*, sphincsharaka128fsimple*, sphincsharaka128srobust, sphincsharaka128ssimple, sphincsharaka192frobust, sphincsharaka192fsimple, sphincsharaka192srobust, sphincsharaka192ssimple, sphincsharaka256frobust, sphincsharaka256fsimple, sphincsharaka256srobust, sphincsharaka256ssimple
• SPHINCS-SHA256:sphincssha256128frobust*, sphincssha256128fsimple, sphincssha256128srobust, sphincssha256128ssimple*, sphincssha256192frobust, sphincssha256192fsimple, sphincssha256192srobust, sphincssha256192ssimple, sphincssha256256frobust, sphincssha256256fsimple, sphincssha256256srobust, sphincssha256256ssimple
• SPHINCS-SHAKE256:sphincsshake256128frobust, sphincsshake256128fsimple*, sphincsshake256128srobust, sphincsshake256128ssimple, sphincsshake256192frobust, sphincsshake256192fsimple, sphincsshake256192srobust, sphincsshake256192ssimple, sphincsshake256256frobust, sphincsshake256256fsimple, sphincsshake256256srobust, sphincsshake256256ssimple

As the underlying liboqs at build time may be configured to not enable all algorithms, it is advisable to check the possible subset of algorithms actually enabled via the standard commands, i.e., openssl list -signature-algorithms -provider oqsprovider and openssl list -kem-algorithms -provider oqsprovider.

In addition, algorithms not denoted with "*" above are not enabled for TLS operations. This designation can be changed by modifying the "enabled" flags in the main algorithm configuration file and re-running the generator script python3 oqs-template/generate.py.

In order to enable parallel use of classic and quantum-safe cryptography this provider also provides different hybrid algorithms, combining classic and quantum-safe methods at their respective bit strength:

• if <KEX> claims NIST L1 or L2 security, oqs-provider provides the methods p256_<KEX> and x25519_<KEX>, which combines <KEX> with EC curve p256 and X25519, respectively.
• if <KEX> claims NIST L3 or L4 security, oqs-provider provides the methods p384_<KEX> and x448_<KEX>, which combines <KEX> with EC curve p384 and X448, respectively.
• if <KEX> claims NIST L5 security, oqs-provider provides the method p521_<KEX>, which combines <KEX> with EC curve p521.

For example, since kyber768 claims NIST L3 security, the hybrids x448_kyber768 and p384_kyber768 are available.

A full list of algorithms, their interoperability code points and OIDs as well as a method to dynamically adapt them are documented in ALGORITHMS.md.

Note: oqsprovider depends for TLS session setup and hybrid operations on OpenSSL providers for classic crypto operations. Therefore it is essential that a provider such as default or fips is configured to be active. See tests/oqs.cnf for an example.

All component builds and testing described in detail below can be executed by running the scripts scripts/fullbuild.sh and scripts/runtests.sh respectively (tested on Linux Ubuntu and Mint as well as OSX).

By default, these scripts always build and test against the current OpenSSL master branch.

These scripts can be configured by setting various environment variables as documented in the scripts. For information the following environment settings may be of most interest:

• OPENSSL_INSTALL: Directory of an existing, non-standard OpenSSL binary distribution
• OPENSSL_BRANCH: Tag of a specific OpenSSL release to be built and used in testing

To be able to build oqsprovider, OpenSSL 3.0 and liboqs need to be installed. It's not important where they are installed, just that they are.

For building, minimum requirements are a C compiler, git access and cmake. For Linux these commands can typically be installed by running for example

sudo apt install build-essential git cmake

If OpenSSL3 is not already installed, the following shows an example for building and installing the latest/master branch of OpenSSL 3 in .local:

git clone git://git.openssl.org/openssl.git
cd openssl
./config --prefix=$(echo $(pwd)/../.local) && make && make install_sw
cd ..

For OpenSSL implementation limitations, e.g., regarding provider feature usage and support, see here.

Example for building and installing liboqs in .local:

git clone https://github.com/open-quantum-safe/liboqs.git
cd liboqs
cmake -DCMAKE_INSTALL_PREFIX=$(pwd)/../.local -S . -B _build
cmake --build _build && cmake --install _build
cd ..

Further liboqs build options are documented here.

oqsprovider using the local OpenSSL3 build as done above can be built for example via the following:

cmake -DOPENSSL_ROOT_DIR=$(pwd)/.local -DCMAKE_PREFIX_PATH=$(pwd)/.local -S . -B _build
cmake --build _build

Core component testing can be run via the following command:

(cd _build; ctest)

Add -V to the ctest command for verbose output.

Note: Some parts of testing depend on OpenSSL components. Be sure to have these available (done automatically by the scripts provided). See the test README for details.

Additional interoperability tests (with OQS-OpenSSL1.1.1) are available in the script scripts/runtests.sh.

A build target to create .deb packaging is available via the standard package target, e.g., executing make package in the _build subdirectory.

In order to reduce the size of the oqsprovider, it is possible to limit the number of algorithms supported, e.g., to the set of NIST standardized algorithms. This is facilitated by setting the liboqs build option -DOQS_ALGS_ENABLED=STD.

By adding the standard CMake option -GNinja the ninja build system can be used, enabling the usual ninja, ninja test, or ninja package commands.

By adding the standard CMake option -DCMAKE_BUILD_TYPE=Release to the oqsprovider build command, debugging output is disabled.

By setting this environment variable, testing of specific algorithm families as listed here can be disabled in testing. For example

OQS_SKIP_TESTS="sphincs" ./scripts/runtests.sh

excludes all algorithms of the "Sphincs" family.

Note: By default, interoperability testing with oqs-openssl111 is no longer performed by default but can be manually enabled in the script scripts/runtests.sh.

By setting -DUSE_ENCODING_LIB=<ON/OFF> at compile-time, oqs-provider can be compiled with with an an external encoding library qsc-key-encoder. Configuring the encodings is done via environment as described in ALGORITHMS.md.

By setting -DNOPUBKEY_IN_PRIVKEY=<ON/OFF> at compile-time, it can be further specified to omit explicitly serializing the public key in a privateKey structure. The default value is OFF.

The following steps have been tested on Windows 10 and 11 using MSYS2 MINGW64 and were successful. However, building with Visual Studio 2019 was unsuccessful (see #47). Note that the process of building on Windows is considered experimental and may need further adjustments. Please report further issues to #47. Despite skipping the testing process, setting up a test server and client with post-quantum cryptography algorithms can still be accomplished.

In order to exercise the oqsprovider, it needs to be explicitly activated. One way to do this is to enable it in the OpenSSL config file. Detailed explanations can be found for example here.

Another alternative is to explicitly request its use on the command line. The following examples use that option. All examples below assume openssl (3.0) to be located in a folder .local in the local directory as per the building examples above. Having OpenSSL(3) installed in a standard location eliminates the need for specific PATH setting as showcased below.

LD_LIBRARY_PATH=.local/lib64 .local/bin/openssl list -providers -verbose -provider-path _build/lib -provider oqsprovider 

This can be facilitated for example by running

LD_LIBRARY_PATH=.local/lib64 .local/bin/openssl req -x509 -new -newkey rsa -keyout rsa_CA.key -out rsa_CA.crt -nodes -subj "/CN=test CA" -days 365 -config openssl/apps/openssl.cnf
LD_LIBRARY_PATH=.local/lib64 .local/bin/openssl genpkey -algorithm rsa -out rsa_srv.key
LD_LIBRARY_PATH=.local/lib64 .local/bin/openssl req -new -newkey rsa -keyout rsa_srv.key -out rsa_srv.csr -nodes -subj "/CN=test server" -config openssl/apps/openssl.cnf
LD_LIBRARY_PATH=.local/lib64 .local/bin/openssl x509 -req -in rsa_srv.csr -out rsa_srv.crt -CA rsa_CA.crt -CAkey rsa_CA.key -CAcreateserial -days 365

This can be facilitated for example by running

LD_LIBRARY_PATH=.local/lib64 .local/bin/openssl s_server -cert rsa_srv.crt -key rsa_srv.key -www -tls1_3 -groups kyber768:frodo640shake -provider-path _build/lib  -provider default -provider oqsprovider

This can be facilitated for example by running

LD_LIBRARY_PATH=.local/lib64 .local/bin/openssl s_client -groups frodo640shake -provider-path _build/lib  -provider default -provider oqsprovider

By issuing the command GET / the quantum-safe crypto enabled OpenSSL3 server returns details about the established connection.

Any available KEM algorithm can be selected by passing it in the -groups option.

Also possible is the creation and verification of quantum-safe digital signatures using CMS.

For creating signed data, two steps are required: One is the creation of a certificate using a QSC algorithm; the second is the use of this certificate (and its signature algorithm) to create the signed data:

Step 1: Create quantum-safe key pair and self-signed certificate:

LD_LIBRARY_PATH=.local/lib64 .local/bin/openssl req -x509 -new -newkey dilithium3 -keyout qsc.key -out qsc.crt -nodes -subj "/CN=oqstest" -days 365 -config openssl/apps/openssl.cnf -provider-path _build/lib -provider oqsprovider -provider default

By changing the -newkey parameter algorithm name any of the supported quantum-safe or hybrid algorithms can be utilized instead of the sample algorithm dilithium3.

Step 2: Sign data:

As the CMS standard requires the presence of a digest algorithm, while quantum-safe crypto does not, in difference to the QSC certificate creation command above, passing a message digest algorithm via the -md parameter is mandatory.

LD_LIBRARY_PATH=.local/lib64 .local/bin/openssl cms -in inputfile -sign -signer qsc.crt -inkey qsc.key -nodetach -outform pem -binary -out signedfile -md sha512 -provider-path _build/lib  -provider default -provider oqsprovider

Data to be signed is to be contained in the file named inputfile. The resultant CMS output is contained in file signedfile. The QSC algorithm used is the same signature algorithm utilized for signing the certificate qsc.crt.

Continuing the example above, the following command verifies the CMS file signedfile and outputs the outputfile. Its contents should be identical to the original data in inputfile above.

LD_LIBRARY_PATH=.local/lib64 .local/bin/openssl cms -verify -CAfile qsc.crt -inform pem -in signedfile -crlfeol -out outputfile -provider-path _build/lib -provider oqsprovider -provider default

Note that it is also possible to build proper QSC certificate chains using the standard OpenSSL calls. For sample code see scripts/oqsprovider-certgen.sh.

Also tested to operate OK is the openssl dgst command. Sample invocations building on the keys and certificate files in the examples above:

LD_LIBRARY_PATH=.local/lib64 .local/bin/openssl dgst -provider-path _build/lib -provider oqsprovider -provider default -sign qsc.key -out dgstsignfile inputfile

LD_LIBRARY_PATH=.local/lib64 .local/bin/openssl dgst -provider-path _build/lib -provider oqsprovider -provider default -signature dgstsignfile -verify qsc.pubkey inputfile

The public key can be extracted from the certificate using standard openssl command:

LD_LIBRARY_PATH=.local/lib64 .local/bin/openssl x509 -provider-path _build/lib -provider oqsprovider -provider default -in qsc.crt -pubkey -noout > qsc.pubkey

The dgst command is not tested for interoperability with oqs-openssl111.

oqsprovider does not implement its own DRBG. Therefore by default it relies on OpenSSL to provide one. Thus, either the default or fips provider must be loaded for QSC algorithms to have access to OpenSSL-provided randomness. Check out OpenSSL provider documentation and/or OpenSSL command line options on how to facilitate this. Or simply use the sample command lines documented in this README.

This dependency could be eliminated by building liboqs without OpenSSL support (OQS_USE_OPENSSL=OFF), which of course would be an unusual approach for an OpenSSL-OQS provider.

The OpenSSL EVP_PKEY_decapsulate API specifies an explicit return value for failure. For security reasons, most KEM algorithms available from liboqs do not return an error code if decapsulation failed. Successful decapsulation can instead be implicitly verified by comparing the original and the decapsulated message.

oqsprovider is written to ensure building on all versions of OpenSSL supporting the provider concept. However, OpenSSL still is in active development regarding features supported via the provider interface. Therefore some functionalities documented above are only supported with specific OpenSSL versions:

In these versions, CMS functionality implemented in providers is not supported: The resolution of openssl/openssl#17717 has not been not getting back-ported to OpenSSL3.0.

Also not supported in this version are provider-based signature algorithms used during TLS1.3 operations as documented in openssl/openssl#10512.

After openssl/openssl#19312 landed, (also PQ) signature algorithms are working in TLS1.3 (handshaking); after openssl/openssl#20486 has landed, also algorithms with very long signatures are supported.

As oqsprovider is dependent on liboqs for the implementation of the PQ algorithms there is a mechanism to adapt the functionality of a specific liboqs version to the current oqsprovider version: The use of the code generator script oqs-template/generate.py which in turn is driven by any of the liboqs release-specific oqs-template/generate.yml[-release] files. The same file(s) also define the (default) TLS IDs of all algorithms included and therefore represent the interoperability level at a specific point in time (of development of oqsprovider and liboqs).

By default, oqsprovider always uses the most current version of liboqs code, but by setting the environment variable "LIBOQS_BRANCH" when running the scripts/fullbuild.sh script, code will be generated to utilize a specific, supported liboqs release. The script scripts/revertmain.sh can be used to revert all code back to the default, main-branch tracking strategy. This can be used, for example, to facilitate a release of oqsprovider to track an old liboqs release.

The Open Quantum Safe project is led by Douglas Stebila and Michele Mosca at the University of Waterloo.

Contributors to the oqsprovider include:

• Michael Baentsch
• Christian Paquin
• Richard Levitte
• Basil Hess
• Julian Segeth
• Alex Zaslavsky

The oqsprovider project is supported through the NGI Assure Fund, a fund established by NLnet with financial support from the European Commission's Next Generation Internet programme, under the aegis of DG Communications Networks, Content and Technology under grant agreement No 957073.

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

We'd like to make a special acknowledgement to the companies who have dedicated programmer time to contribute source code to OQS, including Amazon Web Services, evolutionQ, Microsoft Research, Cisco Systems, and IBM Research.

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 here and here for funding acknowledgments.