PLONK

This is a pure Rust implementation of the PLONK proving system over BLS12-381

This library contains a modularised implementation of KZG10 as the default polynomial commitment scheme.

DISCLAIMER: This library is currently unstable and still needs to go through an exhaustive security analysis. Use at your own risk.

Usage

use dusk_plonk::prelude::*;
use rand_core::OsRng;

// Implement a circuit that checks:
// 1) a + b = c where C is a PI
// 2) a < 2^6
// 3) b < 2^5
// 4) a * b = d where D is a PI
// 5) JubJub::GENERATOR * e(JubJubScalar) = f where F is a Public Input
#[derive(Debug, Default)]
pub struct TestCircuit {
    a: BlsScalar,
    b: BlsScalar,
    c: BlsScalar,
    d: BlsScalar,
    e: JubJubScalar,
    f: JubJubAffine,
}

impl Circuit for TestCircuit {
    fn circuit<C>(&self, composer: &mut C) -> Result<(), Error>
    where
        C: Composer,
    {
        let a = composer.append_witness(self.a);
        let b = composer.append_witness(self.b);

        // Make first constraint a + b = c
        let constraint =
            Constraint::new().left(1).right(1).public(-self.c).a(a).b(b);

        composer.append_gate(constraint);

        // Check that a and b are in range
        composer.component_range(a, 6);
        composer.component_range(b, 5);

        // Make second constraint a * b = d
        let constraint =
            Constraint::new().mult(1).public(-self.d).a(a).b(b);

        composer.append_gate(constraint);

        let e = composer.append_witness(self.e);
        let scalar_mul_result = composer
            .component_mul_generator(e, dusk_jubjub::GENERATOR_EXTENDED)?;

        // Apply the constraint
        composer.assert_equal_public_point(scalar_mul_result, self.f);

        Ok(())
    }
}

let label = b"transcript-arguments";
let pp = PublicParameters::setup(1 << 12, &mut OsRng)
    .expect("failed to setup");

let (prover, verifier) = Compiler::compile::<TestCircuit>(&pp, label)
    .expect("failed to compile circuit");

// Generate the proof and its public inputs
let (proof, public_inputs) = prover
    .prove(&mut OsRng, &TestCircuit::default())
    .expect("failed to prove");

// Verify the generated proof
verifier
    .verify(&proof, &public_inputs)
    .expect("failed to verify proof");

Features

This crate includes a variety of features which will briefly be explained below:

• alloc: Enables the usage of an allocator and with it the capability of performing Proof constructions and verifications. Without this feature it IS NOT possible to prove or verify anything. Its absence only makes dusk-plonk export certain fixed-size data structures such as Proof which can be useful in no_std environments where we don't have allocators either.
• std: Enables std usage as well as rayon parallelization in some proving and verifying ops. It also uses the std versions of the elliptic curve deps, which utilizes the parallel feature from dusk-bls12-381. By default, this is the feature that comes enabled with the crate.
• debug: Enables the runtime debugger backend. Will output CDF files to the path defined in the CDF_OUTPUT environment variable. If used, the binary must be compiled with debug = true. For more info, check the cargo book. The recommended method is to derive the std output, and the std error, and then place them in text file which can be used to efficiently analyse the gates.
• canon: Enables canonical serialization for particular data structures, which is very useful in integrating this library within the rest of the Dusk stack - especially for storage purposes.

Documentation

There are two main types of documentation in this repository:

• Crate documentation. This provides info about all of the functions that the library provides, as well as the documentation regarding the data structures that it exports. To check this, please feel free to go to the documentation page or run make doc or make doc-internal.

• Notes. This is a specific subset of documentation which explains the key mathematical concepts of PLONK and how they work with mathematical demonstrations. To check it, run make doc and open the resulting docs, which will be located under /target with your browser.

Performance

Benchmarks taken on Apple M1, for a circuit-size of 2^16 constraints:

• Proving time: 7.871s
• Verification time: 7.643ms (This time will not vary depending on the circuit-size.)

For more results, please run cargo bench to get a full report of benchmarks in respect of constraint numbers.

Acknowledgements

• Reference implementation AztecProtocol/Barretenberg
• FFT Module and KZG10 Module were taken and modified from zexe/zcash and scipr-lab, respectively.

Licensing

This code is licensed under Mozilla Public License Version 2.0 (MPL-2.0). Please see LICENSE for further info.

About

Implementation designed by the dusk team.

Contributing

• If you want to contribute to this repository/project please, check CONTRIBUTING.md
• If you want to report a bug or request a new feature addition, please open an issue on this repository.