Logos Blockchain Circuits — Rust

Rust bindings for the Logos Blockchain Circuits.

Each circuit has a -sys crate that wraps the underlying C FFI with a safe Rust API.

Crates

Crate	Description
`lbc-poq-sys`	Witness generator for PoQ (Proof of Quota)
`lbc-pol-sys`	Witness generator for PoL (Proof of Leadership)
`lbc-poc-sys`	Witness generator for PoC (Proof of Claim)
`lbc-signature-sys`	Witness generator for Signature
`lbc-types`	Shared types
`lbc-build`	Build helper

Providing the circuit libraries

Each -sys crate needs the compiled circuit library directory for its circuit, containing lib{circuit}.a and witness_generator.dat. There are two ways to provide it, detailed below.

Option A — Prebuilt download

Enable the prebuilt Cargo feature.

The build script downloads the release bundle matching the crate version from GitHub Releases and caches it locally.

[dependencies]
lbc-poq-sys = { version = "0.5", features = ["prebuilt"] }

The cache location depends on the operating system:

Linux: ~/.cache/logos/blockchain/
macOS: ~/Library/Caches/logos/blockchain/
Windows: %LOCALAPPDATA%\logos\blockchain\

The downloaded bundle version always matches CARGO_PKG_VERSION.

Option B — Custom path

Point the build script at any directory containing the compiled circuit libraries:

LBC_POQ_LIB_DIR=/path/to/poq
LBC_POL_LIB_DIR=/path/to/pol
LBC_POC_LIB_DIR=/path/to/poc
LBC_SIGNATURE_LIB_DIR=/path/to/signature
LBC_LIB_DIR=/path/to/lib                 # Directory containing the required libs
                                         # If using a release bundle, this is the included lib/ directory

The justfile at the repo root contains recipes (just poq, just pol, etc.) that build the circuit libraries from source.

This is not yet an officially supported workflow, but it can serve as a reference if you need to produce the libraries yourself.

Usage

In-memory witness generation

use lbc_poq_sys::native::{PoqWitnessInput, generate_witness};
use lbc_types::native::{Error, Witness};

fn main() -> Result<Witness, Error> {
    let inputs_json = std::fs::read_to_string("poq-input.json").expect("failed to read input");
    let input = PoqWitnessInput::new(inputs_json)?;
    generate_witness(&input)
}

File-based witness generation

use lbc_poq_sys::native::generate_witness_from_files;
use lbc_types::native::Error;
use std::path::Path;

fn main() -> Result<(), Error> {
    generate_witness_from_files(
        Path::new("/path/to/witness_generator"),  // Extensionless .dat file
        Path::new("poq-input.json"),
        Path::new("output.wtns"),
    )?;
    Ok(())
}

The other circuits follow the same pattern under lbc_pol_sys, lbc_poc_sys and lbc_signature_sys.

Running tests

cargo test

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