Nethereum.PrivacyPools.Circuits 6.1.0

Nethereum.PrivacyPools.Circuits

Embedded circuit artifacts for the 0xbow Privacy Pools protocol. Provides PrivacyPoolCircuitSource — implements both ICircuitArtifactSource and ICircuitGraphSource, loading compiled Circom circuits from embedded resources with no file-system setup.

Embedded Artifacts

The .wasm files are for JavaScript-based proof generation (snarkjs). The .graph.bin files are for fully native proof generation (circom-witnesscalc + rapidsnark). Both paths use the same .zkey and produce identical proofs.

Usage

var source = new PrivacyPoolCircuitSource();

// Check availability
source.HasCircuit("commitment");   // true — has .wasm, .zkey, .vk
source.HasGraph("commitment");     // true — has .graph.bin

// Load artifacts
byte[] wasm = await source.GetWasmAsync("commitment");       // for snarkjs
byte[] zkey = await source.GetZkeyAsync("commitment");       // for all providers
byte[] graph = source.GetGraphData("commitment");             // for native provider
string vkJson = source.GetVerificationKeyJson("commitment");  // for verification

With Proof Generation

Native (no JavaScript, no Node.js)

Uses iden3/circom-witnesscalc for witness generation and iden3/rapidsnark for proving. Works on desktop, server, and mobile.

var circuitSource = new PrivacyPoolCircuitSource();
var proofProvider = new PrivacyPoolProofProvider(
    new NativeProofProvider(), circuitSource);

var result = await proofProvider.GenerateRagequitProofAsync(
    new RagequitWitnessInput
    {
        Nullifier = commitment.Nullifier,
        Secret = commitment.Secret,
        Value = commitment.Value,
        Label = commitment.Label
    });

Node.js (snarkjs)

var circuitSource = new PrivacyPoolCircuitSource();
var proofProvider = new PrivacyPoolProofProvider(
    new SnarkjsProofProvider(), circuitSource);

Blazor WASM (browser)

var circuitSource = new PrivacyPoolCircuitSource();
var blazorProvider = new SnarkjsBlazorProvider(jsRuntime, "./js/snarkjs.min.mjs");
await blazorProvider.InitializeAsync();
var proofProvider = new PrivacyPoolProofProvider(blazorProvider, circuitSource);

Compiling Circuit Graph Files

The .graph.bin files are pre-compiled and embedded. If you need to recompile them (e.g., after circuit changes), follow these steps.

Prerequisites

• iden3/circom-witnesscalc — build the build-circuit tool:

  git clone https://github.com/iden3/circom-witnesscalc.git
  cd circom-witnesscalc
  cargo build --release -p build-circuit
  

  See Nethereum.CircomWitnessCalc README for build dependencies (Rust, protoc, LLVM/clang).

• 0xbow-io/privacy-pools-core — circuit source and circomlib dependency:

  git clone https://github.com/0xbow-io/privacy-pools-core.git
  cd privacy-pools-core
  npm install
  

Creating wrapper files

The privacy pools circuits use circomkit (no inline component main), so you need wrapper .circom files:

commitment_main.circom:

pragma circom 2.2.0;
include "commitment.circom";
component main {public [value, label]} = CommitmentHasher();

withdrawal_main.circom:

pragma circom 2.2.0;
include "withdraw.circom";
component main {public [withdrawnValue, stateRoot, stateTreeDepth, ASPRoot, ASPTreeDepth, context]} = Withdraw(32);

Compiling

Important: use --O1 optimization level. The default --O2 aggressively reduces signal count, producing graphs incompatible with the existing zkeys. The --O1 level matches circom's default optimization used during trusted setup, producing the correct signal counts (commitment: 1542, withdrawal: 36901).

cd privacy-pools-core/packages/circuits

# Commitment circuit (produces 68 KB graph, 1542 signals)
build-circuit commitment_main.circom commitment.graph.bin \
    -l ../../node_modules -l circuits --O1

# Withdrawal circuit (produces 862 KB graph, 36901 signals)
build-circuit withdrawal_main.circom withdrawal.graph.bin \
    -l ../../node_modules -l circuits --O1

Verifying signal count

The graph signal count must match the zkey. You can verify with circom CLI:

circom commitment_main.circom --r1cs -l ../../node_modules -l circuits
snarkjs r1cs info commitment_main.r1cs
# Should show: # of Wires: 1542

If the graph signal count doesn't match the zkey, rapidsnark will error with: Invalid witness length. Circuit: <expected>, witness: <actual>.

Optimization levels

Placing compiled graphs

Copy the .graph.bin files to the embedded resources directory:

src/Nethereum.PrivacyPools.Circuits/circuits/
    commitment/commitment.graph.bin
    withdrawal/withdrawal.graph.bin

They are automatically embedded by <EmbeddedResource Include="circuits\**\*" /> in the csproj.

Package Relationship

Credits

• 0xbow-io/privacy-pools-core — Privacy Pools circuits
• iden3/circom-witnesscalc — Native witness calculator
• iden3/rapidsnark — Native Groth16 prover
• iden3/circom — Circom circuit compiler