ZK Proof Generation Demos

Two demo applications demonstrate end-to-end Groth16 zero-knowledge proof generation and verification using Nethereum's ZK proof packages and the Privacy Pools commitment circuit.

Both demos include educational UI explaining what ZK proofs are, how Privacy Pools work, and what each step in the pipeline does.

Architecture Overview

                     ┌─────────────────────────────────┐
                     │        Circuit Artifacts          │
                     │   Nethereum.PrivacyPools.Circuits │
                     │  (commitment.wasm / .graph.bin    │
                     │   commitment.zkey, _vk.json)      │
                     └──────────┬──────────┬─────────────┘
                                │          │
              ┌─────────────────┘          └──────────────────┐
              ▼                                               ▼
   ┌──────────────────────┐                    ┌──────────────────────────┐
   │   Browser Path        │                    │   Native Path             │
   │  (Blazor WASM Demo)   │                    │  (Avalonia Desktop Demo)  │
   │                        │                    │                           │
   │  snarkjs (JS interop)  │                    │  CircomWitnessCalc (C)    │
   │  SnarkjsBlazorProvider │                    │  RapidSnarkProver (C++)   │
   └──────────┬─────────────┘                    └──────────┬────────────────┘
              │                                              │
              ▼                                              ▼
   ┌──────────────────────────────────────────────────────────────────┐
   │                    Proof Verification                            │
   │               Nethereum.ZkProofsVerifier                         │
   │          CircomGroth16Adapter.Verify(proof, vk, signals)         │
   │              Pure C# BN128 pairing check                         │
   └──────────────────────────────────────────────────────────────────┘

Blazor WebAssembly Demo

Location: src/demos/Nethereum.ZkProofs.Blazor.Demo/

Uses snarkjs JavaScript running in the browser via Blazor JS interop.

Running

cd src/demos/Nethereum.ZkProofs.Blazor.Demo
dotnet run
# Open http://localhost:5000 in your browser

Pipeline

1. Load — snarkjs is loaded via <script> tag; circuit WASM and zkey are loaded from embedded resources
2. Prove — snarkjs evaluates the WASM circuit and computes the Groth16 proof in JavaScript
3. Verify — CircomGroth16Adapter.Verify() checks the proof in pure C#

Packages

Package	Role
Nethereum.ZkProofs.Snarkjs.Blazor	JS interop with snarkjs for proof generation
Nethereum.PrivacyPools.Circuits	Embedded circuit artifacts
Nethereum.ZkProofsVerifier	Pure C# Groth16 verification

Avalonia Desktop Demo

Location: src/demos/Nethereum.ZkProofs.Avalonia.Demo/

Uses native C/C++ libraries for proof generation — no JavaScript or browser required.

Running

cd src/demos/Nethereum.ZkProofs.Avalonia.Demo
dotnet run

Pipeline

1. Witness — WitnessCalculator.CalculateWitness(graphData, inputsJson) evaluates the circuit constraints natively using circom-witnesscalc
2. Prove — RapidSnarkProver.Prove(zkeyBytes, witnessBytes) generates the Groth16 proof using optimised native multi-scalar multiplication
3. Verify — CircomGroth16Adapter.Verify() checks the proof in pure C#

Packages

Package	Role
Nethereum.CircomWitnessCalc	Native witness generation (NuGet with native DLLs)
Nethereum.ZkProofs.RapidSnark	Native Groth16 proof generation (NuGet with native DLLs)
Nethereum.PrivacyPools.Circuits	Embedded circuit artifacts
Nethereum.ZkProofsVerifier	Pure C# Groth16 verification

Browser vs Native Comparison

Aspect	Browser (Blazor)	Native (Avalonia)
Proof engine	snarkjs (JavaScript)	rapidsnark (C++)
Witness computation	WASM circuit evaluation	circom-witnesscalc (C)
Typical proof time	2-10 seconds	50-500 milliseconds
Platform	Any modern browser	Windows, Linux, macOS, Android
Privacy	Private inputs stay in browser	Private inputs stay on device
Dependencies	snarkjs.min.js (673 KB)	Native DLLs (bundled in NuGet)
Verification	Pure C# (same)	Pure C# (same)

The Privacy Pools Commitment Circuit

Both demos use the same commitment circuit from Nethereum.PrivacyPools.Circuits:

Private inputs (never revealed):

• nullifier — random number for double-spend prevention
• secret — combined with nullifier to create the commitment

Public inputs (visible to verifiers):

• value — deposit amount in wei
• label — Association Set identifier

Public outputs:

• commitmentHash — Hash(nullifier, secret, value, label) — uniquely identifies the deposit on-chain
• nullifierHash — Hash(nullifier) — published on withdrawal to prevent double-spending

The proof demonstrates: "I know a (nullifier, secret) pair that produces this commitment hash" — without revealing the nullifier or secret.