Maybe LibOQS.NET: .NET library for liboqs

LibOQS.NET provides .NET wrapper/bindings for the Open Quantum Safe liboqs C library, which is a C library for quantum-resistant cryptographic algorithms.

This project offers two .NET packages:

• The LibOQS.NET.Native package provides low-level P/Invoke bindings to the liboqs C library
• The LibOQS.NET package offers a high-level, type-safe .NET API for the quantum-resistant algorithms

Both packages are self-contained and include all necessary native dependencies - no manual compilation or native library installation is required.

Quick Start

Installation

Install from NuGet - no additional dependencies or native compilation required:

<PackageReference Include="LibOQS.NET" Version="...version..." />

Or via the .NET CLI:

dotnet add package LibOQS.NET

Basic Usage

using LibOQS.NET;

// LibOQS initializes automatically - no manual Initialize() call needed
try
{
    // Key Encapsulation Mechanism example
    using var kem = new KemInstance(KemAlgorithm.MlKem512);
    
    // Generate keypair
    var (publicKey, secretKey) = kem.GenerateKeypair();
    
    // Encapsulate a shared secret
    var (ciphertext, sharedSecret1) = kem.Encapsulate(publicKey);
    
    // Decapsulate the shared secret
    var sharedSecret2 = kem.Decapsulate(secretKey, ciphertext);
    
    // Verify they match
    Console.WriteLine($"Shared secrets match: {sharedSecret1.SequenceEqual(sharedSecret2)}");
    
    // Digital signature example
    using var sig = new SigInstance(SigAlgorithm.MlDsa44);
    
    // Generate signature keypair
    var (sigPublicKey, sigSecretKey) = sig.GenerateKeypair();
    
    // Sign a message
    var message = System.Text.Encoding.UTF8.GetBytes("Hello, post-quantum world!");
    var signature = sig.Sign(message, sigSecretKey);
    
    // Verify the signature
    var isValid = sig.Verify(message, signature, sigPublicKey);
    Console.WriteLine($"Signature valid: {isValid}");
}
finally
{
    // Optional cleanup - called automatically at app shutdown
    LibOqs.Cleanup();
}

Signed Key Exchange Example

using LibOQS.NET;

try
{
    using var sigAlg = new SigInstance(SigAlgorithm.MlDsa44);
    using var kemAlg = new KemInstance(KemAlgorithm.MlKem512);
    
    // A's long-term secrets
    var (aSigPk, aSigSk) = sigAlg.GenerateKeypair();
    // B's long-term secrets  
    var (bSigPk, bSigSk) = sigAlg.GenerateKeypair();

    // A -> B: kem_pk, signature
    var (kemPk, kemSk) = kemAlg.GenerateKeypair();
    var signature1 = sigAlg.Sign(kemPk, aSigSk);

    // B -> A: kem_ct, signature
    if (!sigAlg.Verify(kemPk, signature1, aSigPk))
        throw new Exception("Failed to verify A's signature");
        
    var (kemCt, bKemSs) = kemAlg.Encapsulate(kemPk);
    var signature2 = sigAlg.Sign(kemCt, bSigSk);

    // A verifies, decapsulates, now both have kem_ss
    if (!sigAlg.Verify(kemCt, signature2, bSigPk))
        throw new Exception("Failed to verify B's signature");
        
    var aKemSs = kemAlg.Decapsulate(kemSk, kemCt);
    
    // Verify shared secrets match
    if (aKemSs.SequenceEqual(bKemSs))
        Console.WriteLine("Key exchange successful!");
}
finally
{
    LibOqs.Cleanup();
}

Features

• Key Encapsulation Mechanisms (KEMs): ML-KEM, Kyber, BIKE, HQC, NTRU, Classic McEliece, NTRU Prime, FrodoKEM (standard/salted and ephemeral eFrodoKEM)
• Digital Signatures: ML-DSA, SLH-DSA, Falcon, MAYO, CROSS, UOV, SNOVA, MQOM
• New Features: Support for context strings in signatures and derandomized (deterministic) operations in KEM.
• Type-safe API: Strong typing with enums for algorithms and proper resource management
• Memory management: Automatic cleanup of native resources using IDisposable pattern
• Cross-platform: Supports Windows x64, Windows ARM64, macOS ARM64, Linux x64, and Linux ARM64
• Self-contained: No manual native library installation or compilation required

Supported Algorithms

Key Encapsulation Mechanisms (KEMs)

• ML-KEM (NIST standardized): ML-KEM-512, ML-KEM-768, ML-KEM-1024
• Kyber: Kyber512, Kyber768, Kyber1024
• BIKE: BIKE-L1, BIKE-L3, BIKE-L5
• HQC: HQC-1, HQC-3, HQC-5
• NTRU: NTRU-HPS-2048-509, NTRU-HPS-2048-677, NTRU-HPS-4096-821, NTRU-HPS-4096-1229, NTRU-HRSS-701, NTRU-HRSS-1373
• Classic McEliece: All 10 variants (e.g., 348864, 460896, 6688128, 6960119, 8192128 with fast variants)
• NTRU Prime: sntrup761
• FrodoKEM (standard, salted variant): FrodoKEM-640-AES, FrodoKEM-640-SHAKE, FrodoKEM-976-AES, FrodoKEM-976-SHAKE, FrodoKEM-1344-AES, FrodoKEM-1344-SHAKE
• eFrodoKEM (ephemeral variant): eFrodoKEM-640-AES, eFrodoKEM-640-SHAKE, eFrodoKEM-976-AES, eFrodoKEM-976-SHAKE, eFrodoKEM-1344-AES, eFrodoKEM-1344-SHAKE

Digital Signatures

• ML-DSA (NIST standardized): ML-DSA-44, ML-DSA-65, ML-DSA-87
• SLH-DSA (NIST standardized): All 12 pure variants (SHA2 and SHAKE, 128/192/256, fast/small)
• Falcon: Falcon-512, Falcon-1024, Falcon-Padded-512, Falcon-Padded-1024
• MAYO: MAYO-1, MAYO-2, MAYO-3, MAYO-5
• CROSS: All 18 variants (RSDP/RSDPG, Balanced/Fast/Small)
• UOV: All 12 variants (Ip, Is, III, V; with pkc/skc variants)
• SNOVA: All 12 variants
• MQOM: All 12 variants (mqom2_cat1/3/5_gf16_fast/short_r3/r5)

Algorithm Availability

Not all algorithms may be available in every build of liboqs. You can check if an algorithm is enabled:

if (KemAlgorithm.MlKem512.IsEnabled())
{
    // Use ML-KEM-512
    using var kem = new KemInstance(KemAlgorithm.MlKem512);
    // ...
}

Memory Management

The library properly manages native resources:

• Automatic initialization: LibOQS initializes automatically via static constructor
• Automatic cleanup: Use using statements with KemInstance and SigInstance
• Optional manual cleanup: Call LibOqs.Cleanup() when completely done with the library

Thread Safety

The native liboqs library is generally thread-safe for read operations but may not be thread-safe for initialization. It's recommended to:

• Use separate instances of KemInstance and SigInstance per thread
• The automatic initialization is thread-safe
• Call LibOqs.Cleanup() once at application shutdown if needed

Error Handling

The library throws specific exceptions:

• OqsException: General OQS operation failures
• AlgorithmNotSupportedException: When an algorithm is not enabled
• ArgumentException: Invalid parameters
• ObjectDisposedException: Using disposed objects

Building from Source (For Development)

The NuGet packages are self-contained and don't require building from source. This section is only for developers who want to contribute or modify the library.

Prerequisites

• .NET 9.0 SDK or later
• CMake 3.5 or later
• C/C++ compiler (Visual Studio Build Tools on Windows, GCC/Clang on Linux/macOS)
• Git with submodule support

Clone with Submodules

This repository uses git submodules to include the liboqs library. Clone with submodules:

git clone --recursive https://github.com/filipw/maybe-liboqs-dotnet.git
cd maybe-liboqs-dotnet

If you already cloned without --recursive, initialize the submodules:

git submodule init
git submodule update

Building

1. Build the native liboqs library:

   On Windows, run the PowerShell script:

   .\build-dotnet-liboqs.ps1

   On Linux, run the bash script:

   ./build-dotnet-liboqs-linux.sh

   On Mac, use:

   ./build-dotnet-liboqs-macos.sh

   This will:

   • Configure and build liboqs as a shared library
   • Copy the resulting DLL/so/dylib to the appropriate directories
   • Enable all common quantum-resistant algorithms (ML-KEM, ML-DSA, SLH-DSA, Kyber, Falcon, FrodoKEM, BIKE, HQC, NTRU, SNOVA, MQOM, etc.)

2. Build the .NET libraries:

   dotnet build

3. Run tests:

   dotnet test

4. Run examples:

   cd src/Examples
   dotnet run

Submodule Management

This project uses liboqs 0.16.0-rc1 as a git submodule.

Update to latest liboqs version:

cd liboqs
git fetch
git checkout <new-tag>
cd ..
git add liboqs
git commit -m "Update liboqs to <new-tag>"

Working with submodules:

# Initialize submodules after cloning
git submodule init
git submodule update

# Update all submodules to latest commits
git submodule update --remote

# Clone with all submodules
git clone --recursive <repo-url>

Platform Support

LibOQS.NET supports the following platforms out of the box with no additional setup required:

• Windows x64
• Windows ARM64
• Linux x64
• Linux ARM64
• macOS ARM64

Note

Platform Limitations:

• Windows: SLH-DSA (Pure variants) and MQOM are currently disabled due to known bugs in liboqs 0.16.0-rc1 that cause a stack overflow during signing on Windows. BIKE is also disabled on Windows.
• macOS: MQOM is disabled because its short variants overflow the stack during signing in liboqs 0.16.0-rc1.

The NuGet packages include all necessary native libraries for these platforms.

Troubleshooting

AlgorithmNotSupportedException

This means the algorithm you're trying to use was not enabled when liboqs was compiled. You can:

1. Check which algorithms are enabled using the .IsEnabled() method
2. Use a different algorithm that is available

General Issues

If you encounter issues:

1. Ensure you're using a supported platform (see Platform Support above)
2. Check that your .NET runtime version is compatible (.NET 9.0 or later)
3. Verify the algorithm you're trying to use is enabled with .IsEnabled()

Contributing

1. Fork the repository
2. Create a feature branch
3. Make your changes
4. Ensure tests pass: dotnet test
5. Submit a pull request

When working with submodules:

• Keep liboqs submodule updates in separate commits
• Test thoroughly after submodule updates
• Update documentation if API changes occur

Security Considerations

⚠️ Important: This library is intended for prototyping and evaluation purposes. The quantum-resistant algorithms are still under standardization and may change. For production use, consider hybrid approaches that combine post-quantum algorithms with traditional cryptography.

License

LibOQS.NET is licensed under the MIT license.

The included liboqs library is covered by its own license.

Acknowledgments

• Open Quantum Safe project
• liboqs C library
• The quantum cryptography research community