Nethereum.ZkProofs.RapidSnark

Nethereum.ZkProofs.RapidSnark

Native Groth16 proof generation for .NET using iden3/rapidsnark. Significantly faster than snarkjs — no Node.js dependency.

Pair with Nethereum.CircomWitnessCalc for a fully native ZK proof pipeline (witness generation + proving, zero JavaScript).

How It Works

RapidSnark is a fast C++ Groth16 prover. It takes a proving key (.zkey) and a witness (.wtns) and outputs a proof. It does NOT generate witnesses — that's handled by Nethereum.CircomWitnessCalc.

This package provides three levels of API:

Usage

NativeProofProvider (recommended — full pipeline, no JS)

Drop-in replacement for SnarkjsProofProvider. Handles witness generation (via CircomWitnessCalc) and proof generation (via RapidSnark) in one call.

var provider = new NativeProofProvider();

var result = await provider.FullProveAsync(new ZkProofRequest
{
    CircuitZkey = File.ReadAllBytes("circuit.zkey"),
    CircuitGraph = File.ReadAllBytes("circuit.graph.bin"),  // from build-circuit --O1
    InputJson = """{"nullifier":"123","secret":"456","value":"1000","label":"1"}""",
});

Console.WriteLine(result.ProofJson);
Console.WriteLine(result.PublicSignalsJson);

With embedded circuit artifacts

When your circuit source provides both ICircuitArtifactSource and ICircuitGraphSource (e.g. PrivacyPoolCircuitSource), the proof provider automatically uses the graph for native witness generation:

var circuitSource = new PrivacyPoolCircuitSource(); // embeds .zkey + .graph.bin
var proofProvider = new PrivacyPoolProofProvider(new NativeProofProvider(), circuitSource);

// Fully native — no Node.js, no JavaScript
var result = await proofProvider.GenerateRagequitProofAsync(witnessInput);

RapidSnarkProofProvider (pre-computed witness)

When you already have the witness bytes (e.g. from an external witness generator):

var provider = new RapidSnarkProofProvider();

var result = await provider.FullProveAsync(new ZkProofRequest
{
    CircuitZkey = zkeyBytes,
    WitnessBytes = witnessBytes,  // .wtns binary
});

RapidSnarkProver (low-level, reusable zkey)

For batch proving — load the zkey once, prove many times:

using var prover = new RapidSnarkProver();
prover.LoadZkey(zkeyBytes);

var (proof1, public1) = prover.ProveWithLoadedZkey(witness1);
var (proof2, public2) = prover.ProveWithLoadedZkey(witness2);
var (proof3, public3) = prover.ProveWithLoadedZkey(witness3);

Native verification

bool valid = RapidSnarkVerifier.Verify(proofJson, publicSignalsJson, verificationKeyJson);

Supported Platforms

Pre-built native binaries included (from Nethereum/rapidsnark CI and iden3/rapidsnark releases v0.0.8):

Performance

Measured on Windows x64 with a Groth16 circuit (~3,800 constraints):

Both providers produce identical public signals and both proofs verify via Groth16 BN128 pairing check.

Updating Native Binaries

Native binaries are built by the CI workflow at Nethereum/rapidsnark (the windows-support branch adds Windows builds to the upstream CI):

# Download all artifacts from a CI run
gh run download <run-id> -R Nethereum/rapidsnark

# Copy to package runtimes
cp rapidsnark-windows-x86_64/lib/librapidsnark.dll  runtimes/win-x64/native/rapidsnark.dll
cp rapidsnark-linux-x86_64/lib/librapidsnark.so     runtimes/linux-x64/native/
cp rapidsnark-linux-arm64/lib/librapidsnark.so       runtimes/linux-arm64/native/
cp rapidsnark-macOS-arm64/lib/librapidsnark.dylib    runtimes/osx-arm64/native/
cp rapidsnark-macOS-x86_64/lib/librapidsnark.dylib   runtimes/osx-x64/native/
cp rapidsnark-Android/lib/librapidsnark.so            runtimes/android-arm64/native/

Building from Source

All platforms (CI)

The Nethereum/rapidsnark fork (windows-support branch) has a GitHub Actions workflow that builds for Windows, Linux (x64/arm64), macOS (x64/arm64), Android, and iOS. See WINDOWS_BUILD.md in that repo for full details.

Windows (MSYS2/MinGW64)

# Install MSYS2
winget install MSYS2.MSYS2

# In MSYS2 MinGW64 shell:
pacman -S --noconfirm mingw-w64-x86_64-gcc mingw-w64-x86_64-cmake make m4 diffutils tar xz curl

# Clone and build
git clone --recursive https://github.com/Nethereum/rapidsnark.git
cd rapidsnark
git checkout windows-support
./build_gmp.sh windows
make windows_x86_64
# Output: package_windows_x86_64/lib/librapidsnark.dll

Linux / macOS

git clone --recursive https://github.com/iden3/rapidsnark.git
cd rapidsnark
bash build_gmp.sh host        # or macos_arm64, macos_x86_64
make host                     # or macos_arm64, macos_x86_64

Package Relationship

Nethereum.CircomWitnessCalc          Nethereum.ZkProofs.RapidSnark (this)
  |                                    |
  |  graph + inputs --> witness        |  zkey + witness --> proof
  |  (circom-witnesscalc native)       |  (rapidsnark native)
  |                                    |
  +-------- NativeProofProvider -------+
            (combines both into IZkProofProvider)

Credits

• iden3/rapidsnark — Fast native Groth16 prover (C++)
• iden3/circom-witnesscalc — Native witness calculator (Rust with C FFI)
• iden3/circom — Circom circuit compiler