cairo-felt

⚡ Cairo-vm ⚡

A faster and safer implementation of the Cairo VM in Rust

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Table of Contents

• Disclaimer
• About
  • The Cairo language
• Getting Started
  • Dependencies
• Usage
  • Adding cairo-vm as a dependency
  • Running cairo-vm from the CLI
  • Using hints
  • Running a function in a Cairo program with arguments
  • WebAssembly Demo
  • Testing
• Benchmarks
• Changelog
• Contributing
• Related Projects
• Documentation
  • Cairo
  • Original Cairo VM Internals
  • Compilers and Interpreters
  • StarkNet
  • Computational Integrity and Zero-Knowledge Proofs
• License

⚠️ Disclaimer

🚧 cairo-vm is still being built therefore breaking changes might happen often so use it at your own risk. 🚧 Cargo doesn't comply with semver, so we advise to pin the version to 0.1.0. This can be done adding cairo-vm = "0.1.0" to your Cargo.toml

📖 About

Cairo VM is the virtual machine for the Cairo language.

There's an older version of Cairo VM written in Python, which is currently in production.

This repository contains the newer version, written in Rust. It's faster and has safer and more expressive typing. Once completed, it will replace the older one as the sole Cairo VM.

The Cairo language

Cairo is the first production-grade platform for generating STARK proofs for general computation.

It's Turing-complete and it was created by Starkware as part of the Starknet ecosystem.

🌅 Getting Started

Dependencies

Required

These are needed in order to compile and use the project.

• Rust 1.69.0 or newer
• Cargo

Optional

These dependencies are only necessary in order to run the original VM, compile Cairo programs, and run tests.

• make
• PyEnv

Installation script

You can install all of the required and optional dependencies by running the script install.sh while in the repository root.

🚀 Usage

Adding cairo-vm as a dependency

You can add the following to your rust project's Cargo.toml:

cairo-vm = { version = '0.7.0', features = ["lambdaworks-felt"] }

The features = ["lambdaworks-felt"] part adds usage of lambdaworks-math as the backend for Felt252. This improves performance by more than 20%, and will be the default in the future.

Running cairo-vm from CLI

To run programs from the command line, first compile the repository from the cairo-vm-cli folder:

cd cairo-vm-cli; cargo build --release -F lambdaworks-felt; cd ..

The -F lambdaworks-felt part adds usage of lambdaworks-math as the backend for Felt252. This improves performance by more than 20%, and will be the default in the future.

Once the binary is built, it can be found in target/release/ under the name cairo-rvm-cli.

To compile a program, use cairo-compile [path_to_the_.cairo_file] --output [desired_path_of_the_compiled_.json_file]. For example:

cairo-compile cairo_programs/abs_value_array.cairo --output cairo_programs/abs_value_array_compiled.json

To run a compiled .json program through the VM, call the executable giving it the path and name of the file to be executed. For example:

target/release/cairo-vm-cli cairo_programs/abs_value_array_compiled.json --layout all_cairo

The flag --layout determines which builtins can be used. More info about layouts here.

To sum up, the following code will get you from zero to running a Cairo program:

git clone https://github.com/lambdaclass/cairo-vm.git

cd cairo-vm

cargo build --release

cairo-compile cairo_programs/abs_value_array.cairo --output cairo_programs/abs_value_array_compiled.json

target/release/cairo-vm-run cairo_programs/abs_value_array_compiled.json --layout all_cairo

Using hints

Currently, as this VM is under construction, it's missing some of the features of the original VM. Notably, this VM only implements a limited number of Python hints at the moment, while the Python Cairo VM allows users to run any Python code.

There are two ways to use non-standard hints in this VM:

• Extend the cairo-vm code and build your own binary using the interface HintProcessor.
• Use cairo-vm-py which supports running any hint in a Python interpreter.

Running a function in a Cairo program with arguments

When running a Cairo program directly using the Cairo-vm repository you would first need to prepare a couple of things.

1. Specify the Cairo program you want to run

let program =
        Program::from_file(Path::new(&file_path), None);

2. Instantiate the VM, the cairo_runner, the hint processor, and the entrypoint

let mut vm = VirtualMachine::new(false);

let mut cairo_runner = CairoRunner::new(&program, "all_cairo", false);

let mut hint_processor = BuiltinHintProcessor::new_empty();

let entrypoint = program
        .identifiers
        .get(&format!("__main__.{}", &func_name))?
        .pc;

3. Lastly, initialize the builtins and segments.

cairo_runner.initialize_builtins(&mut vm)?;
cairo_runner.initialize_segments(&mut vm, None);

When using cairo-vm with the Starknet devnet there are additional parameters that are part of the OS context passed on to the run_from_entrypoint method that we do not have here when using it directly. These parameters are, for example, initial stacks of the builtins, which are the base of each of them and are needed as they are the implicit arguments of the function.

 let _var = cairo_runner.run_from_entrypoint(
            entrypoint,
            vec![
                &MaybeRelocatable::from(2).into(),  //this is the entry point selector
                &MaybeRelocatable::from((2,0)).into() //this would be the output_ptr for example if our cairo function uses it
                ],
            false,
            &mut vm,
            &mut hint_processor,
        );

WebAssembly Demo

A demo on how to use cairo-vm with WebAssembly can be found here.

Testing

To run the test suite you'll need cargo-llvm-cov dependency so make sure to run this command beforehand:

make deps

Now that you have the dependencies necessary to run the test suite you can run:

make test

📊 Benchmarks

Running a Cairo program that gets the 1.5 millionth Fibonacci number we got the following benchmarks:

• Execution time with Criterion
• Flamegraph
• Github action results

Note before running the benchmark suite: the benchmark named iai_benchmark depends on Valgrind. Please make sure it is installed prior to running the iai_benchmark benchmark.

Run the complete benchmark suite with cargo:

cargo bench

Run only the criterion_benchmark benchmark suite with cargo:

cargo bench --bench criterion_benchmark

Run only the iai_benchmark benchmark suite with cargo:

cargo bench --bench iai_benchmark

📜 Changelog

Keeps track of the latest changes here.

🛠 Contributing

The open-source community is a fantastic place for learning, inspiration, and creation, and this is all thanks to contributions from people like you. Your contributions are greatly appreciated.

If you have any suggestions for how to improve the project, please feel free to fork the repo and create a pull request, or open an issue with the tag 'enhancement'.

1. Fork the Project
2. Create your Feature Branch (git checkout -b feat/AmazingFeature)
3. Commit your Changes (git commit -m 'feat: add some AmazingFeature')
4. Push to the Branch (git push origin feat/AmazingFeature)
5. Open a Pull Request

And don't forget to give the project a star! ⭐ Thank you again for your support.

You can find more detailed instructions in the CONTRIBUTING.md document.

🌞 Related Projects

• starknet_in_rust: implementation of Starknet in Rust, powered by the cairo-vm.
• cairo-vm-py: Bindings for using cairo-vm from Python code.

📚 Documentation

Cairo

• From Cairo Documentation: How Cairo Works
• Cairo – a Turing-complete STARK-friendly CPU architecture
• A Verified Algebraic Representation of Cairo Program Execution
• Cairo Verifier in Rust

Original Cairo VM Internals

We wrote a document explaining how the Cairo VM works. It can be found here.

Compilers and Interpreters

This is a list of recommended books to learn how to implement a compiler or an interpreter.

• How I wrote my own "proper" programming language - Mukul Rathi
• Introduction to Compilers and Language Design - Douglas Thain
• Beautiful Racket - Matthew Flatt
• Crafting interpreters - Robert Nystrom
• Engineering a Compiler - Keith D. Cooper, Linda Torczon

StarkNet

• StarkNet's Architecture Review

Computational Integrity and Zero Knowledge Proofs

Basics

• Intro to zero-knowledge proofs
• Security and Privacy for Crypto with Zero-Knowledge Proofs
• A Hands-On Tutorial for Zero-Knowledge Proofs Series

ZK SNARKs

• What are zk-SNARKs?
• Vitalik's introduction to how zk-SNARKs are possible
• Vitalik's post on quadratic arithmetic programs
• Why and How zk-SNARK Works - Maksym Petkus
• Comparing General Purpose zk-SNARKs
• Dark forest's intro + circuits PART 1
• Dark forest's intro + circuits PART 2

STARKs

Introduction:

• Cryptography Stack Exchange Answer
• Hasu gets STARK-pilled - with Eli Ben-Sasson
• Cairo for Blockchain Developers
• Why STARKs are the key to unlocking blockchain scalability
• STARKs whitepaper: Scalable, transparent, and post-quantum secure computational integrity
• STARKs vs. SNARKs: A Cambrian Explosion of Crypto Proofs

Vitalik Buterin's blog series on zk-STARKs:

• STARKs, part 1: Proofs with Polynomials
• STARKs, part 2: Thank Goodness it's FRI-day
• STARKs, part 3: Into the Weeds

Alan Szepieniec's STARK tutorial:

• Anatomy of a STARK

StarkWare's STARK Math blog series:

• STARK Math: The Journey Begins
• Arithmetization I
• Arithmetization II
• Low Degree Testing
• A Framework for Efficient STARKs

⚖️ License

This project is licensed under the Apache 2.0 license.

See LICENSE for more information.