SCOSSL - The SymCrypt engine for OpenSSL

The SymCrypt engine for OpenSSL (SCOSSL) allows the use of OpenSSL with SymCrypt as the provider for core cryptographic operations. It leverages the OpenSSL engine interface to override the cryptographic implementations in OpenSSL's libcrypto.so with SymCrypt's implementations. The primary motivation for this is to support FIPS certification, as vanilla OpenSSL 1.1.1 does not have a FIPS-certified cryptographic module.

Where possible the SCOSSL will direct OpenSSL API calls to the SymCrypt FIPS module. In cases where SymCrypt cannot (currently) support an OpenSSL API, the best effort is made to fall-back to the default OpenSSL implementation of the given function. In a few cases the engine will instead fail the call completely, as re-routing to OpenSSL's implementation is not always easy, and as with any project we have to prioritize!

Important note: The code in this repository is currently undergoing validation for use in Microsoft-internal products. At this time, it has not been tested for use in other environments and should not be considered production-ready.

Algorithms that will be routed to a FIPS certifiable SymCrypt module with this version

The following list is not necessarily exhaustive, and will be updated as more functionality is added to SCOSSL. Note that just because an algorithm is FIPS certifiable, does not mean it is recommended for use. SSH-KDF implementation is disabled by default and can be enabled by adding -DSCOSSL_SSHKDF=1 argument to CMake. This algorithm also requires OpenSSL source code in the build process.

• Key derivation
  • HKDF (SHA1, SHA2-256, SHA2-384, SHA2-512)
  • TLS 1.2 KDF (SHA1, SHA2-256, SHA2-384, SHA2-512)
  • SSH-KDF (SHA1, SHA2-256, SHA2-384, SHA2-512)
• Key Agreement
  • ECDH (P256, P384, P521)
  • Finite Field DH (ffdhe2048, ffdhe3072, ffdhe4096, modp2048, modp3072, modp4096)
• Hashing
  • SHA1
  • SHA2-256
  • SHA2-384
  • SHA2-512
• Message Authentication
  • HMAC (SHA1, SHA2-256, SHA2-384, SHA2-512)
• Symmetric
  • AES (128, 192, 256)
    • CBC, CCM, ECB, GCM
• Asymmetric
  • RSA (2048, 3072, 4096)
    • PKCS1, OAEP, PSS
  • ECDSA (P256, P384, P521)

Known cases where SCOSSL will fail rather than fallback to default OpenSSL

1. Use of an AES-GCM IV which is not 12-bytes (96-bits)
2. Use of unsupported digests in RSA signatures, TLS PRF, and HMAC
3. Use of multi-prime (more than 2-prime) RSA

Versioning and Servicing

As of version 1.0.0, SCOSSL uses the versioning scheme defined by the Semantic Versioning 2.0.0 specification. This means:

• Major version changes introduce ABI and/or API breaking changes
• Minor version changes introduce backwards compatible additional functionality or improvements, and/or bug fixes
• Patch version changes introduce backwards compatible bug fixes

Regarding servicing, our strong recommendation is that distro vendors and application developers regularly update to the latest version of SymCrypt and SymCrypt engine for both security fixes and functionality/performance improvements.

We will support long-term servicing of specific releases for security fixes. Details of this plan will be released publicly in the future.

Building Instructions

Compilation Instructions

1. Install libssl, or compile and install OpenSSL from source
2. Follow Linux build instructions from SymCrypt repository SymCrypt to build the Linux SymCrypt module
   • You can either install the Linux SymCrypt module (i.e libsymcrypt.so* to /usr/lib/, and inc/* to /usr/include/), or
   • Copy the built module to the root of the SymCrypt-OpenSSL repo cp <SymCryptRepo>/bin/module/<arch>/LinuxUserMode/<module_name>/libsymcrypt.so ./
3. mkdir bin; cd bin
4. cmake .. -DCMAKE_TOOLCHAIN_FILE=../cmake-toolchain/LinuxUserMode-<arch>.cmake
   • If you have not installed SymCrypt header files, you can also specify the root directory -DSYMCRYPT_ROOT_DIR=<SymCryptRepo>
   • If you want to link to a specific OpenSSL installation, you can also specify -DOPENSSL_ROOT_DIR=<OpensslInstallDirectory>
   • Optionally, for a release build, specify -DCMAKE_BUILD_TYPE=Release
5. cmake --build .
   • Optionally specify -jN where N is the number of processes you wish to spawn for the build

Run Samples

./SslPlay/SslPlay

Contributing

This project welcomes contributions and suggestions. Most contributions require you to agree to a Contributor License Agreement (CLA) declaring that you have the right to, and actually do, grant us the rights to use your contribution. For details, visit https://cla.opensource.microsoft.com.

When you submit a pull request, a CLA bot will automatically determine whether you need to provide a CLA and decorate the PR appropriately (e.g., status check, comment). Simply follow the instructions provided by the bot. You will only need to do this once across all repos using our CLA.

This project has adopted the Microsoft Open Source Code of Conduct. For more information see the Code of Conduct FAQ or contact opencode@microsoft.com with any additional questions or comments.

Trademarks

This project may contain trademarks or logos for projects, products, or services. Authorized use of Microsoft trademarks or logos is subject to and must follow Microsoft's Trademark & Brand Guidelines. Use of Microsoft trademarks or logos in modified versions of this project must not cause confusion or imply Microsoft sponsorship. Any use of third-party trademarks or logos are subject to those third-party's policies.