> [!IMPORTANT]
> `main` is the development branch.
> When building applications or running examples, use the [latest release](https://github.com/risc0/risc0/releases) instead.

<p align="center">
  <a href="https://risczero.com" target="_blank">
    <picture>
      <source media="(prefers-color-scheme: dark)" srcset="https://risczero.com/companies/risczero_dark.svg">
      <img src="https://risczero.com/companies/risczero.svg" alt="RISC Zero Company Logo" width="142" height="126">
    </picture>
  </a>
</p>

[![Crates.io][crates-badge]][crates-url]
[![Dual licensed: Apache-2.0 OR MIT][licence-badge]][licence-url]
[![Build Status][actions-badge]][actions-url]
[![Discord chat][discord-badge]][discord-url]
[![Twitter][twitter-badge]][twitter-url]

RISC Zero is a zero-knowledge verifiable general computing platform based on
[zk-STARKs][zk-proof] and the [RISC-V] microarchitecture.

A [zero knowledge proof][zk-proof] allows one party (the prover) to convince
another party (the verifier) that something is true without revealing all the
details. In the case of RISC Zero, the prover can show that they correctly executed
some code (known to both parties), while only revealing to the verifier the
output of the code, not any of its inputs or any state during execution.

The code runs in a special virtual machine, called a _zkVM_. The RISC Zero zkVM
emulates a small [RISC-V] computer, allowing it to run arbitrary code in any
language, so long as a compiler toolchain exists that targets RISC-V. Currently,
SDK support exists for Rust, C, and C⁠+⁠+.

## Protocol overview and terminology

First, the code to be proven must be compiled from its implementation language
into a _method_. A method is represented by a RISC-V ELF file with a special
entry point that runs the code of the method. Additionally, one can compute for
a given method its _image ID_ which is a special type of cryptographic hash of
the ELF file, and is required for verification.

Next, the host program runs and proves the method inside the zkVM. The logical
RISC-V machine running inside the zkVM is called the _guest_ and the prover
running the zkVM is called the _host_. The guest and the host can communicate
with each other during the execution of the method, but the host cannot modify
the execution of the guest in any way, or the proof being generated will be
invalid. During execution, the guest code can write to a special append-only log
called the _journal_ which represents the official output of the computation.

Presuming the method terminated correctly, a _receipt_ is produced, which
provides the proof of correct execution. This receipt consists of 2 parts: the
journal written during execution and a blob of opaque cryptographic data called
the _seal_.

The verifier can then verify the receipt and examine the log. If any tampering
was done to the journal or the seal, the receipt will fail to verify.
Additionally, it is cryptographically infeasible to generate a valid receipt
unless the output of the journal is the exactly correct output for some valid
execution of the method whose image ID matches the receipt. In summary, the
receipt acts as a zero-knowledge proof of correct execution.

Because the protocol is zero-knowledge, the verifier cannot infer anything about
the details of the execution or any data passed between the host and the guest
(aside from what is implied by the data written to the journal and the correct
execution of the code).

## Security

This code implements a [three-layer recursive proof system][zksummit10-talk],
based on the well-studied zk-STARK protocol and Groth16 protocol. An overview of
the underlying cryptographic assumptions can be found on our [Security
Model][security-model] page. With default parameters, this system achieves
perfect zero-knowledgeness and 98 bits of conjectured security. Our STARK
protocol is described in [Scalable, Transparent Arguments of RISC-V
Integrity][proof-system-in-detail], and a soundness/security calculator is
included in the `soundness.rs` file.

To run the calculator, use `RUST_LOG=risc0_zkp=debug` when running a proof.

## Getting Started

To start your own project, you can use our `cargo risczero` tool to write the
initial boilerplate and set up a standard directory structure.

First, [install Rust][install-rust] if you don't already have it, then install
the RISC Zero toolchain installer, `rzup`. We'll use `rzup` to install
`cargo-risczero`.

To install `rzup` run the following command and follow the instructions:

```bash
curl -L https://risczero.com/install | bash
```

Next we can install the RISC Zero toolchain by running `rzup install`:

```bash
rzup install
```

You can verify the installation was successful by running:

```bash
cargo risczero --version
```

After installation, you can create a new project (named `my_project` in this example):

```bash
cargo risczero new my_project
```

More details and options for `cargo risczero` are given in
[its README][cargo-risczero-readme].

For more guidance on how to use RISC Zero, how RISC Zero projects are typically
structured, and other resources useful to developers new to RISC Zero, see our
[Getting Started page][quickstart].

## Documentation

Documentation for the zkVM SDK and other Rust crates can be found at [docs.rs/risc0-zkvm](https://docs.rs/risc0-zkvm).
All other documentation can be found at [dev.risczero.com](https://dev.risczero.com).

You can build and view the Rust documentation locally by using `cargo doc`.
See [CONTRIBUTING.md](./CONTRIBUTING.md) for dependencies.
Source code for the documentation website can be found in the [website directory](./website).

## Building from source

Building from source requires some additional tools and steps.
Please refer to [CONTRIBUTING.md](./CONTRIBUTING.md) for the full instructions.

## Rust Binaries

| crate          | [crates.io]                                                                                         |
| -------------- | --------------------------------------------------------------------------------------------------- |
| cargo-risczero | [![x](https://img.shields.io/badge/crates.io-v2.1-orange)](https://crates.io/crates/cargo-risczero) |
| risc0-r0vm     | [![x](https://img.shields.io/badge/crates.io-v2.1-orange)](https://crates.io/crates/risc0-r0vm)     |
| risc0-tools    | [![x](https://img.shields.io/badge/crates.io-v2.0-orange)](https://crates.io/crates/risc0-tools)    |

## Rust Libraries

| crate                       | [crates.io]                                                                                                      | [docs.rs](https://docs.rs)                                                                                    |
| --------------------------- | ---------------------------------------------------------------------------------------------------------------- | ------------------------------------------------------------------------------------------------------------- |
| bonsai-sdk                  | [![x](https://img.shields.io/badge/crates.io-v1.4-orange)](https://crates.io/crates/bonsai-sdk)                  | [![](https://img.shields.io/docsrs/bonsai-sdk)](https://docs.rs/bonsai-sdk)                                   |
| risc0-binfmt                | [![x](https://img.shields.io/badge/crates.io-v2.0-orange)](https://crates.io/crates/risc0-binfmt)                | [![](https://img.shields.io/docsrs/risc0-binfmt)](https://docs.rs/risc0-binfmt)                               |
| risc0-build                 | [![x](https://img.shields.io/badge/crates.io-v2.1-orange)](https://crates.io/crates/risc0-build)                 | [![](https://img.shields.io/docsrs/risc0-build)](https://docs.rs/risc0-build)                                 |
| risc0-build-kernel          | [![x](https://img.shields.io/badge/crates.io-v2.0-orange)](https://crates.io/crates/risc0-build-kernel)          | [![](https://img.shields.io/docsrs/risc0-build-kernel)](https://docs.rs/risc0-build-kernel)                   |
| risc0-circuit-recursion     | [![x](https://img.shields.io/badge/crates.io-v2.0-orange)](https://crates.io/crates/risc0-circuit-recursion)     | [![](https://img.shields.io/docsrs/risc0-circuit-recursion)](https://docs.rs/risc0-circuit-recursion)         |
| risc0-circuit-recursion-sys | [![x](https://img.shields.io/badge/crates.io-v2.0-orange)](https://crates.io/crates/risc0-circuit-recursion-sys) | [![](https://img.shields.io/docsrs/risc0-circuit-recursion-sys)](https://docs.rs/risc0-circuit-recursion-sys) |
| risc0-circuit-rv32im        | [![x](https://img.shields.io/badge/crates.io-v2.0-orange)](https://crates.io/crates/risc0-circuit-rv32im)        | [![](https://img.shields.io/docsrs/risc0-circuit-rv32im)](https://docs.rs/risc0-circuit-rv32im)               |
| risc0-circuit-rv32im-sys    | [![x](https://img.shields.io/badge/crates.io-v2.0-orange)](https://crates.io/crates/risc0-circuit-rv32im-sys)    | [![](https://img.shields.io/docsrs/risc0-circuit-rv32im-sys)](https://docs.rs/risc0-circuit-rv32im-sys)       |
| risc0-core                  | [![x](https://img.shields.io/badge/crates.io-v2.0-orange)](https://crates.io/crates/risc0-core)                  | [![](https://img.shields.io/docsrs/risc0-core)](https://docs.rs/risc0-core)                                   |
| risc0-groth16               | [![x](https://img.shields.io/badge/crates.io-v2.0-orange)](https://crates.io/crates/risc0-groth16)               | [![](https://img.shields.io/docsrs/risc0-groth16)](https://docs.rs/risc0-groth16)                                |
| risc0-sys                   | [![x](https://img.shields.io/badge/crates.io-v1.4-orange)](https://crates.io/crates/risc0-sys)                   | [![](https://img.shields.io/docsrs/risc0-sys)](https://docs.rs/risc0-sys)                                     |
| risc0-zkp                   | [![x](https://img.shields.io/badge/crates.io-v2.0-orange)](https://crates.io/crates/risc0-zkp)                   | [![](https://img.shields.io/docsrs/risc0-zkp)](https://docs.rs/risc0-zkp)                                     |
| risc0-zkvm                  | [![x](https://img.shields.io/badge/crates.io-v2.1-orange)](https://crates.io/crates/risc0-zkvm)                  | [![](https://img.shields.io/docsrs/risc0-zkvm)](https://docs.rs/risc0-zkvm)                                   |
| risc0-zkvm-platform         | [![x](https://img.shields.io/badge/crates.io-v2.0-orange)](https://crates.io/crates/risc0-zkvm-platform)         | [![](https://img.shields.io/docsrs/risc0-zkvm-platform)](https://docs.rs/risc0-zkvm-platform)                 |

## Feature flags

The following feature flags are present in one or more of the crates listed above:

| Feature          | Target(s)         | Implies    | Description                                                                                                                                                  | Crates                                                               |
| ---------------- | ----------------- | ---------- | ------------------------------------------------------------------------------------------------------------------------------------------------------------ | -------------------------------------------------------------------- |
| client           | all except rv32im | std        | Enables the client API.                                                                                                                                      | risc0-zkvm                                                           |
| cuda             |                   | prove, std | Enables CUDA GPU acceleration for the prover. Requires CUDA toolkit to be installed.                                                                         | risc0-circuit-recursion, risc0-circuit-rv32im, risc0-zkp, risc0-zkvm |
| disable-dev-mode | all except rv32im |            | Disables dev mode so that proving and verifying may not be faked. Used to prevent a misplaced `RISC0_DEV_MODE` from breaking security in production systems. | risc0-zkvm                                                           |
| metal            | macos             | prove, std | Deprecated - Metal GPU acceleration is enabled by default on Apple Silicon.                                                                                  | risc0-circuit-recursion, risc0-circuit-rv32im, risc0-zkp, risc0-zkvm |
| prove            | all except rv32im | std        | Enables the prover, incompatible within the zkvm guest.                                                                                                      | risc0-circuit-recursion, risc0-circuit-rv32im, risc0-zkp, risc0-zkvm |
| std              | all               |            | Support for the Rust stdlib.                                                                                                                                 | risc0-circuit-recursion, risc0-circuit-rv32im, risc0-zkp, risc0-zkvm |

## License

This project is dual-licensed under either:

* [Apache License, Version 2.0](LICENSE-APACHE)
* [MIT License](LICENSE-MIT)

[actions-badge]: https://img.shields.io/github/actions/workflow/status/risc0/risc0/main.yml?branch=main
[actions-url]: https://github.com/risc0/risc0/actions?query=workflow%3ACI+branch%3Amain
[cargo-risczero-readme]: https://github.com/risc0/risc0/blob/main/risc0/cargo-risczero/README.md
[crates-badge]: https://img.shields.io/badge/crates.io-v2.0-orange
[crates-url]: https://crates.io/crates/risc0-zkvm
[crates.io]: https://crates.io
[discord-badge]: https://img.shields.io/discord/953703904086994974.svg?logo=discord&style=flat-square
[discord-url]: https://discord.gg/risczero
[install-rust]: https://doc.rust-lang.org/cargo/getting-started/installation.html
[licence-badge]: https://img.shields.io/badge/license-Apache--2.0_OR_MIT-blue
[licence-url]: #license
[proof-system-in-detail]: https://dev.risczero.com/proof-system-in-detail.pdf
[quickstart]: https://dev.risczero.com/api/zkvm/quickstart
[risc-v]: https://en.wikipedia.org/wiki/RISC-V
[security-model]: https://dev.risczero.com/api/security-model
[twitter-badge]: https://img.shields.io/twitter/follow/risczero
[twitter-url]: https://twitter.com/risczero
[zk-proof]: https://en.wikipedia.org/wiki/Non-interactive_zero-knowledge_proof
[zksummit10-talk]: https://www.youtube.com/watch?v=wkIBN2CGJdc