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Submit a Noir Ultraplonk Proof

In this tutorial, we will walk through the process of submitting a Ultraplonk proof generated by Noir.

Note: Recursive proofs are not supported at this time.

Requirements​

Before starting, ensure you have the following tools installed:

  • noirup: Follow the installation instructions here.
  • bb: Follow in the installation instructions here
  • noir-cli tool. 
      git clone https://github.com/HorizenLabs/ultraplonk_verifier
      cargo install --features bins --path .
    (Note: This may take 20-25 mins when running for the first time)

Setting the Nargo Version​

To set the correct version of nargo, run:

noirup -v <version>

Verify the version with:

nargo --version

Make sure to select a bb version compatible with the selected nargo one.

Noir v0.30.0​

Create a New Noir Project​

Refer to the Noir documentation for instructions on creating a new project and generating proving artifacts.

Generating the Solidity Verifier Contract​

Generate the Solidity verifier contract by running:

nargo codegen-verifier

This will create a file named plonk_vk.sol in the ./contract/hello_world directory and a proof file named hello_world.proof in the ./target directory. Your project structure should look like this:

$ tree
.
├── Nargo.toml
├── Prover.toml
├── Verifier.toml
├── contract
│   └── hello_world
│       └── plonk_vk.sol
├── proofs
│   └── hello_world.proof
└── src
    └── main.nr

Creating the Proof Data JSON File​

Create a new file named proof.json in your project’s root directory with the following content:

{
  "proof": "0x...",
  "verifyInputs": ["0x..."]
}

Replace the proof and verifyInputs fields with the values from the hello_world.proof and Verifier.toml files, respectively.

Generating Proving Artifacts​

To generate the proving artifacts, execute the following commands:

noir-cli key --input ./contract/hello_world/plonk_vk.sol --output ./target/vk.bin
noir-cli proof-data --input-json ./proof.json --output-proof ./target/proof.bin --output-pubs ./target/pubs.bin

To get also the vk in hexadecimal format, run:

noir-cli key-to-hex --input <input_vk_path> --output <output_vk_hex_path>

To make sure the proving artifacts are generated correctly, run:

noir-cli verify --key ./target/vk.bin --proof ./target/proof.bin --pubs ./target/pubs.bin

These commands will generate the necessary files for submitting the Ultraplonk proof.

Noir v0.31.0​

Starting from Noir 0.31.0 the nargo toolchain has been slightly modified and the Barretenberg backend has been exposed as a separate CLI (bb) and used for the process of proof creation and verification; moreover, bb also allows to explicitly export the verification key. This makes the process of getting the proving artifacts less contrived with respect to the previous version.

Refer to the Noir documentation for instructions on creating a new project and generating proving artifacts.

Once you get the proof and vk files from nargo and bb, execute the following commands:

noir-cli proof-datav2 -n <num_public_inputs> --input-proof <proof_path> --output-proof <out_proof_path> --output-pubs <out_pubs_path>

This command will provide the proof and public_input files in binary format. The same files in hexadecimal format are also generated, for ease of submission to zkVerify.

To get also the vk in hexadecimal format, run:

noir-cli key-to-hex --input <input_vk_path> --output <output_vk_hex_path>

To make sure that everything works correctly, run:

noir-cli verify --key <vk_bin_path> --proof <proof_bin_path> --pubs <pubs_bin_path>

Submitting the Proof​

Submit the proof by using polkadot.js.org frontend like on the image below:

Submit Proof