Bonsai Foundry Template

Note: This software is not production ready. Do not use in production.

Starter template for writing an application using Bonsai.

This repository implements an application on Ethereum utilizing Bonsai as a coprocessor to the smart contract application. It provides a starting point for building powerful new applications on Ethereum that offload computationally intensive, or difficult to implement, tasks to be proven by the RISC Zero zkVM, with verifiable results sent to your Ethereum contract.

For a 60 second overview of how this template and off-chain computation with Bonsai work, check out the video here.

Overview

The picture below shows a simplified overview of how users can integrate Bonsai into their Ethereum smart contracts:

1. Users can delegate their smart contract's logic to Bonsai. The Bonsai Relay Contract provides a Request Callback interface. This interface, accessible both off-chain (through HTTP REST API) and on-chain, emits an event detected by the Ethereum Bonsai Relayer.
2. The Ethereum Bonsai Relayer sends the proof request to Bonsai.
3. Bonsai generates a Snark proof and its result, encapsulated in a journal.
4. The Ethereum Bonsai Relayer submits this proof and journal on-chain to the Bonsai Relay Contract for validation.
5. If validated, the journal is dispatched to the user's smart contract via the specified callback.

Dependencies

First, install Rust and Foundry, and then restart your terminal. Next, you will need to install the cargo risczero tool. We'll use cargo binstall to get cargo-risczero installed. See cargo-binstall for more details.

cargo install cargo-binstall
cargo binstall cargo-risczero

Next we'll need to install the risc0 toolchain with:

cargo risczero install

Quick Start

First, install the RISC Zero toolchain using the instructions above.

Now, you can initialize a new Bonsai project at a location of your choosing:

forge init -t risc0/bonsai-foundry-template ./my-project

Congratulations! You've just built your first Bonsai project. Your new project consists of:

• a zkVM program (written in Rust), which specifies a computation that will be proven
• a contract (written in Solidity), which receives the response

Requesting a proof can be done via both off-chain or on-chain requests.

Test Your Project

• Use cargo build to test compilation of your zkVM program.
• Use cargo test to run the tests in your zkVM program.
• Use forge test to test your Solidity contracts and their interaction with your zkVM program.

Configuring Bonsai

Note: The Bonsai proving service is still in early Alpha. To request an API key complete the form here.

With the Bonsai proving service, you can produce a Groth16 SNARK proof that is verifiable on-chain. You can get started by setting the following environment variables with your API key and associated URL.

export BONSAI_API_KEY="YOUR_API_KEY" # see form linked above
export BONSAI_API_URL="BONSAI_URL" # provided with your api key

Now if you run forge test with RISC0_DEV_MODE=false, the test will run as before, but will additionally use the fully verifying BonsaiRelay contract instead of BonsaiTestRelay and will request a SNARK receipt from Bonsai.

RISC0_DEV_MODE=false forge test

Next Steps

To build your application, you'll need to make changes in two folders:

• write the code you want proven in the methods folder
• write the on-chain part of your project in the contracts folder

Then, you're ready to deploy your project.

Project Structure

Below are the primary files in the project directory

.
├── Cargo.toml                      // Definitions for cargo and rust
├── foundry.toml                    // Definitions for foundry
├── contracts                       // Your Ethereum contracts live here
│   ├── BonsaiStarter.sol           // Starter template for basic callback contract
│   └── BonsaiStarterLowLevel.sol   // Starter template for low-level callback contract
├── tests                           // Your Ethereum contract tests live here
│   ├── BonsaiStarter.t.sol         // Tests for basic callback contract
│   └── BonsaiStarterLowLevel.t.sol // Tests for low-level callback contract
└── methods                         // [zkVM guest programs] are built here
    ├── Cargo.toml
    ├── build.rs                    // Instructions for the risc0-build rust crate
    ├── guest                       // A rust crate containing your [zkVM guest programs]
    │   ├── Cargo.toml
    │   └── src
    │       └── bin                 // Your [zkVM guest programs] live here
    │           └── fibonacci.rs    // Example [guest program] for fibonacci number calculation
    └── src
        ├── main.rs                 // Glue binary for locally testing Bonsai applications
        └── lib.rs                  // Built RISC Zero guest programs are compiled into here