Plonky3 is a toolkit for implementing polynomial IOPs (PIOPs), such as PLONK and STARKs. It aims to support several polynomial commitment schemes, such as Brakedown.

This is the "core" repo, but the plan is to move each crate into its own repo once APIs stabilize.

Status

Fields:

• Mersenne31
  • "complex" extension field
  • ~128 bit extension field
  • AVX2
  • AVX-512
  • NEON
• BabyBear
  • ~128 bit extension field
  • AVX2
  • AVX-512
  • NEON
• Goldilocks
  • ~128 bit extension field

Generalized vector commitment schemes

• generalized Merkle tree

Polynomial commitment schemes

• FRI-based PCS
• tensor PCS
• univariate-to-multivariate adapter
• multivariate-to-univariate adapter

PIOPs

• univariate STARK
• multivariate STARK
• PLONK

Codes

• Brakedown
• Reed-Solomon

Interpolation

• Barycentric interpolation
• radix-2 DIT FFT
• radix-2 Bowers FFT
• four-step FFT
• Mersenne circle group FFT

Hashes

• Rescue
• Poseidon
• Poseidon2
• BLAKE3
  • modifications to tune BLAKE3 for hashing small leaves
• Keccak-256
• Monolith

Benchmarks

Many variations are possible, with different fields, hashes and so forth, which can be controlled through the command line.

For example, to prove 2^20 Poseidon2 permutations of width 16, using the KoalaBear field, Radix2DitParallel DFT and KeccakF as the Merkle tree hash:

RUSTFLAGS="-Ctarget-cpu=native" cargo run --example prove_monty_31 --release --features parallel -- --field koala-bear --objective poseidon-2-permutations --log-trace-length 17 --discrete-fourier-transform radix-2-dit-parallel --merkle-hash keccak-f

Currently the options for the command line arguments are:

• --field (-f): koala-bear or baby-bear.
• --objective (-o): blake-3-permutations, poseidon-2-permutations, keccak-f-permutations.
• --log-trace-length (-l): Accepts any integer between 0 and 255. The number of permutations proven is trace_length, 8*trace_length and trace_length/24 for blake3, poseidon2 and keccakf respectively.
• --discrete-fourier-transform (-d): radix-2-dit-parallel, recursive-dft.
• --merkle-hash (-m): poseidon-2, keccak-f.

Extra speedups may be possible with some configuration changes:

• JEMALLOC_SYS_WITH_MALLOC_CONF=retain:true,dirty_decay_ms:-1,muzzy_decay_ms:-1 will cause jemalloc to hang on to virtual memory. This may not affect the very first proof much, but can help significantly with subsequent proofs as fewer pages (if any) will need to be newly assigned by the OS. These settings might not be suitable for all production environments, e.g. if the process' virtual memory is limited by ulimit or max_map_count.
• Adding lto = "fat" in the top-level Cargo.toml may improve performance slightly, at the cost of longer compilation times.

CPU features

Plonky3 contains optimizations that rely on newer CPU instructions that are not available in older processors. These instruction sets include x86's BMI1 and 2, AVX2, and AVX-512. Rustc does not emit those instructions by default; they must be explicitly enabled through the target-feature compiler option (or implicitly by setting target-cpu). To enable all features that are supported on your machine, you can set target-cpu to native. For example, to run the tests:

RUSTFLAGS="-Ctarget-cpu=native" cargo test

Support for some instructions, such as AVX-512, is still experimental. They are only available in the nightly build of Rustc and are enabled by the nightly-features feature flag. To use them, you must enable the flag in Rustc (e.g. by setting target-feature) and you must also enable the nightly-features feature.

Nightly-only optimizations

Some optimizations (in particular, AVX-512-optimized math) rely on features that are currently available only in the nightly build of Rustc. To use them, you need to enable the nightly-features feature. For example, to run the tests:

cargo test --features nightly-features

Known issues

The verifier might panic upon receiving certain invalid proofs.

License

Licensed under either of

• Apache License, Version 2.0, (LICENSE-APACHE or http://www.apache.org/licenses/LICENSE-2.0)
• MIT license (LICENSE-MIT or http://opensource.org/licenses/MIT)

at your option.

Guidance for external contributors

Do you feel keen and able to help with Plonky3? That's great! We encourage external contributions!

We want to make it easy for you to contribute, but at the same time we must manage the burden of reviewing external contributions. We are a small team, and the time we spend reviewing external contributions is time we are not developing ourselves.

We also want to help you to avoid inadvertently duplicating work that is already underway, or building something that we will not want to incorporate.

First and foremost, please keep in mind that this is a highly technical piece of software and contributing is only suitable for experienced mathematicians, cryptographers and software engineers.

The Polygon Zero Team reserves the right to accept or reject any external contribution for any reason, including a simple lack of time to maintain it (now or in the future); we may even decline to review something that is not considered a sufficiently high priority for us.

To avoid disappointment, please communicate your intention to contribute openly, while respecting the limited time and availability we have to review and provide guidance for external contributions. It is a good idea to drop a note in our public Discord #development channel of your intention to work on something, whether an issue, a new feature, or a performance improvement. This is probably all that's really required to avoid duplication of work with other contributors.

What follows are some more specific requests for how to write PRs in a way that will make them easy for us to review. Deviating from these guidelines may result in your PR being rejected, ignored or forgotten.

General guidance for your PR

Obviously PRs will not be considered unless they pass our Github CI. The Github CI is not executed for PRs from forks, but you can simulate the Github CI by running the commands in .github/workflows/ci.yml.

Under no circumstances should a single PR mix different purposes: Your PR is either a bug fix, a new feature, or a performance improvement, never a combination. Nor should you include, for example, two unrelated performance improvements in one PR. Please just submit separate PRs. The goal is to make reviewing your PR as simple as possible, and you should be thinking about how to compose the PR to minimise the burden on the reviewer.

Plonky3 uses stable Rust, so any PR that depends on unstable features is likely to be rejected. It's possible that we may relax this policy in the future, but we aim to minimize the use of unstable features; please discuss with us before enabling any.

Here are a few specific guidelines for the three main categories of PRs that we expect:

The PR fixes a bug

In the PR description, please clearly but briefly describe

1. the bug (could be a reference to a GH issue; if it is from a discussion (on Discord/email/etc. for example), please copy in the relevant parts of the discussion);
2. what turned out to the cause the bug; and
3. how the PR fixes the bug.

Wherever possible, PRs that fix bugs should include additional tests that (i) trigger the original bug and (ii) pass after applying the PR.

The PR implements a new feature

If you plan to contribute an implementation of a new feature, please double-check with the Polygon Zero team that it is a sufficient priority for us that it will be reviewed and integrated.

In the PR description, please clearly but briefly describe

1. what the feature does
2. the approach taken to implement it

All PRs for new features must include a suitable test suite.

The PR improves performance

Performance improvements are particularly welcome! Please note that it can be quite difficult to establish true improvements for the workloads we care about. To help filter out false positives, the PR description for a performance improvement must clearly identify

1. the target bottleneck (only one per PR to avoid confusing things!)
2. how performance is measured
3. characteristics of the machine used (CPU, OS, #threads if appropriate)
4. performance before and after the PR

Licensing

Unless you explicitly state otherwise, any contribution intentionally submitted for inclusion in the work by you, as defined in the Apache-2.0 license, shall be dual licensed as above, without any additional terms or conditions.