🧮 Noir Basics Example

An example repository demonstrating how to verify Noir circuits using a Solidity verifier and the bb backend.

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🗂️ Project Structure

• /circuits — Contains the Noir circuit and logic.
• /contract — Foundry project with Solidity verifier and test contract.
• /js — JavaScript code for generating and saving proofs using bb.js.

Tested with:

• Noir v1.0.0-beta.3
• bb CLI v0.82.2

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🧠 Circuit Logic

The Noir circuit proves that: $x * 2 + y ==$ expected

Where:

• x is a private input
• y and expected are public inputs

This lets a user prove correctness without revealing their private input x.

Circuit Logic

The Noir circuit checks if x * 2 + y == expected, where:

• x is a private input
• y and expected are public inputs

Installation / Setup

# Foundry
git submodule update

# Build circuits, generate verifier contract
(cd circuits && ./build.sh)

# Install JS dependencies
(cd js && yarn)

Proof generation in JS

# Use bb.js to generate proof and save to a file
(cd js && yarn generate-proof)

# Run foundry test to read generated proof and verify
(cd contract && forge test --optimize --optimizer-runs 5000 --gas-report -vvv)

Proof generation with bb cli

cd circuits

# Generate witness
nargo execute

# Generate proof
bb prove -b ./target/noir_solidity.json -w target/noir_solidity.gz -o ./target --oracle_hash keccak

# Split this proof and public inputs into two files

# Convert proof to hex, and slice first 4 bytes of metadata
PROOF_HEX=$(cat ./target/proof | od -An -v -t x1 | tr -d $' \n' | sed 's/^.\{8\}//')

NUM_PUBLIC_INPUTS=2
HEX_PUBLIC_INPUTS=${PROOF_HEX:0:$((32 * $NUM_PUBLIC_INPUTS * 2))}
SPLIT_HEX_PUBLIC_INPUTS=$(sed -e 's/.\{64\}/0x&,/g' <<<$HEX_PUBLIC_INPUTS)
PROOF_WITHOUT_PUBLIC_INPUTS="${PROOF_HEX:$((NUM_PUBLIC_INPUTS * 32 * 2))}"

# Save proof and public inputs to files
echo $PROOF_WITHOUT_PUBLIC_INPUTS | xxd -r -p > ./target/proof
echo "[\"$SPLIT_HEX_PUBLIC_INPUTS\"]" > ./target/public-inputs

# Run foundry test to read generated proof and verify
cd ..
(cd contract && forge test --optimize --optimizer-runs 5000 --gas-report -vvv)

🔁 Dual Workflow Support (CLI and JS)

The project supports two approaches for generating proofs:

• JavaScript-based workflow using bb.js
• CLI-based workflow using nargo and bb directly

▶️ Running the Circuit and Tests

Use the run.sh script with an argument to select the approach:

# JavaScript workflow using bb.js
./circuits/run.sh js

# CLI workflow using nargo + bb
./circuits/run.sh cli

This script will:

1. Build the circuit
2. Generate a proof
3. Run Solidity tests using Foundry

🛠 Building the Solidity Verifier

Use the build.sh script to compile the circuit and generate the Solidity verifier:

./build.sh

This will:

• Compile the Noir circuit
• Generate the verification key (vk)
• Export the Solidity verifier to contract/Verifier.sol

🧭 Ecosystem Attribution

This project is indexed in the Electric Capital Crypto Ecosystems Map.

Source: Electric Capital Crypto Ecosystems
Link: https://github.com/electric-capital/crypto-ecosystems
Logo:

💡 If you’re working in open source crypto, submit your repository here to be counted.

Thank you for contributing and for reading the contribution guide! ❤️