# Halo2

<details>

<summary>Prerequisites</summary>

#### WASM pack

Ensure you have `wasm-pack` installed:

```sh
curl https://rustwasm.github.io/wasm-pack/installer/init.sh -sSf | sh
```

</details>

## Build the prover

### Clone the W3bstream repository

Start by cloning the W3bstream repository, where you can start from a template example:

```sh
git clone https://github.com/iotexproject/w3bstream.git
cd examples/halo2-circuit/
```

Open the folder in a code editor and make the required modifications based on your actual data message.

### Build the circuit

```sh
wasm-pack build --target nodejs --out-dir pkg
```

{% hint style="info" %}
[-> Go to the official Halo2 documentation to learn how to build Halo2 circuits](https://zcash.github.io/halo2/user/simple-example.html)
{% endhint %}

The circuit bytecode is saved in the file  `halo2_wasm_bg.wasm` located under the `pkg` folder.

{% hint style="success" %}
[-> Go to the **Create a W3bstream Project** section to create a W3bstream configuration file based on this circuit](/depin/iotex-depin-modules/w3bstream/build-with-w3bstream/deploy-to-w3bstream.md)
{% endhint %}

### Build the circuit executable

The command below will create thasdfwefe circuit executable that can be used to generate and verify proofs locally, as well as generate the Solidity contract for on-chain verification of a proof:

```shell
cargo build --release
```

<table data-view="cards"><thead><tr><th></th></tr></thead><tbody><tr><td><a href="/pages/rs0w6PDac8L1QChzFv5X">-> Go to the <strong>Create a W3bstream Project</strong> section to create a W3bstream configuration file based on this prover</a></td></tr><tr><td><a href="/pages/qfSq4RuufwfS0tCkiNn2">→ See the <strong>On-chain Verification</strong> section to learn how to verify Risc Zero proofs</a></td></tr></tbody></table>

{% hint style="success" %}

{% endhint %}

{% hint style="success" %}

{% endhint %}


---

# Agent Instructions: Querying This Documentation

If you need additional information that is not directly available in this page, you can query the documentation dynamically by asking a question.

Perform an HTTP GET request on the current page URL with the `ask` query parameter:

```
GET https://docs.iotex.io/depin/iotex-depin-modules/w3bstream/build-with-w3bstream/build-the-prover-code/halo2.md?ask=<question>
```

The question should be specific, self-contained, and written in natural language.
The response will contain a direct answer to the question and relevant excerpts and sources from the documentation.

Use this mechanism when the answer is not explicitly present in the current page, you need clarification or additional context, or you want to retrieve related documentation sections.