Crate falcon_multisig 

falcon-multisig

Production-grade post-quantum threshold multisignature library based on Falcon-512 (NIST FIPS 206 / FN-DSA).

Overview

This library provides M-of-N threshold signature schemes built entirely on Falcon-512, the lattice-based signature algorithm standardised by NIST. It is designed to be:

• Chain-agnostic — no dependency on any specific blockchain runtime or VM.
• Production-ready — extracted from and validated against a live PQC blockchain (QuantaChain) running Falcon-512 at the consensus layer.
• WASM-compatible — uses falcon-rust (pure Rust, no C FFI) throughout.
• Misuse-resistant — domain separation on all signed data; secret keys are zeroized on drop.

Threat Model

The cryptographic security reduces to the hardness of the NTRU problem and the Short Integer Solution (SIS) problem over NTRU lattices — both believed to be quantum-resistant under current knowledge. No classical or known quantum algorithm breaks Falcon-512 with fewer than 2^128 operations.

Quick Start

use falcon_multisig::{KeyPair, ThresholdConfig, SigningSession};

// Generate a 2-of-3 committee
let keypairs: Vec<KeyPair> = (0..3).map(|_| KeyPair::generate()).collect();
let public_keys: Vec<_> = keypairs.iter().map(|kp| kp.public_key().clone()).collect();

let config = ThresholdConfig::new(2, public_keys).unwrap();

// Each signer produces a partial signature
let message = b"transfer:alice:bob:1000";
let mut session = SigningSession::new(&config, message);

session.add_signature(0, keypairs[0].sign(message)).unwrap();
session.add_signature(1, keypairs[1].sign(message)).unwrap();

// Verify the complete threshold signature
assert!(session.verify().unwrap());

Feature Flags

Feature	Default	Description
std	yes	Enables std-dependent APIs and error formatting
serde	yes	Enables JSON serialization of all public types

Security Notes

• Never reuse a KeyPair across incompatible domain contexts — always pass the full message payload to KeyPair::sign, not a pre-hashed digest.
• Domain separation (FALCON_MULTISIG_V1:) is prepended internally before signing.
• All secret key bytes are zeroized when a KeyPair is dropped.

Re-exports

pub use address::MultisigAddress;

pub use error::Error;

pub use keypair::KeyPair;

pub use session::SigningSession;

pub use threshold::ThresholdConfig;

pub use verify::verify_partial;

Modules

address

Address derivation for single keys and M-of-N committees.

error

Error types for the falcon-multisig library.

keypair

Falcon-512 keypair — signing and public key management.

session

Signing session — stateful collection and verification of threshold signatures.

threshold

Threshold configuration for an M-of-N Falcon-512 committee.

verify

Core verification primitive for Falcon-512 signatures.

Constants

DOMAIN_TAG

The domain separation tag prepended to every message before signing.

PUBLIC_KEY_BYTES

Byte length of a Falcon-512 public key.

SIGNATURE_MAX_BYTES

Maximum byte length of a raw Falcon-512 signature.

SIGNATURE_MIN_BYTES

Minimum byte length of a valid raw Falcon-512 signature.