zerostyl-verifier

zerostyl-verifier is a no_std Rust library crate (no CLI binary) that implements halo2-KZG proof verification for the Arbitrum Stylus runtime. It embeds the KZG parameters and a serialized verifying key at build time, so verification needs no runtime keygen.

Not a binary

zerostyl-verifier is a dependency you add to a Stylus contract project, not a command you run. It is not installed alongside the CLI tools.

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Adding it to a project

zerostyl-verifier is not published to crates.io — depend on the repository via git. The workspace also patches halo2_proofs to the PSE fork, which a consumer must replicate:

[dependencies]
zerostyl-verifier = { git = "https://github.com/kazai777/zerostyl", default-features = false }
stylus-sdk = "0.9.0"

[patch.crates-io]
halo2_proofs = { git = "https://github.com/privacy-scaling-explorations/halo2.git", tag = "v0.3.0" }

The crate is no_std and requires an allocator; the Stylus SDK provides one when building for wasm32-unknown-unknown.

Features

Feature	Effect
std (default)	Host build; embeds the reference verifying key
stylus	Pulls stylus-sdk + alloy-primitives for a Stylus target
embedded_vk	Embed the KZG params + serialized VK at build time
state_mask_vk	Additionally embed the state_mask circuit's VK and expose verify_state_mask_bytes

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API

// Reference verifier (embedded VK + params).
pub fn verify(proof: &[u8], public_inputs: &[u8]) -> Result<bool, Vec<u8>>;

// With the `state_mask_vk` feature: verify a state_mask proof.
// `public_inputs` are 32-byte little-endian field representations (Fr::to_repr()).
#[cfg(feature = "state_mask_vk")]
pub fn verify_state_mask_bytes(
    proof: &[u8],
    public_inputs: &[[u8; 32]],
) -> Result<bool, Vec<u8>>;

Each returns Ok(true) when the proof verifies, Ok(false) when it does not, and Err(_) when an input is malformed (for example a non-canonical field element).

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On-chain size

Not deployable as-is

The crate compiles for wasm32-unknown-unknown, but a full halo2-KZG verifier exceeds Arbitrum Stylus's 24 KB Brotli-compressed contract limit (the state_mask verifier is ~240 KB compressed). It is a correct, tested reference verifier, not a deployable contract. The deployed demo contracts record a proof hash instead. Use zerostyl-orbit to check an artifact's size against a given chain, and see Verifier Integration for the honest on-chain model and the paths (BN254-precompile / Groth16 wrap) that would fit the budget.