Keymaster Multisig Rust Library

Rust v4 implementation of the Keymaster Multisig library using native Rust cryptography and WebAssembly bindings.

Features

• Multi-signature Support: Create M-of-N multi-signature scripts
• Script Generation: Generate P2MS (Pay-to-Multi-Signature) locking scripts
• Signature Creation: Generate individual and combined signatures
• Arbitrated Pool: Buyer/Seller/Arbiter v4 funding, state, signing, verification, and merge APIs
• Cross-Validation: Byte-compatible with the TypeScript and Go implementations
• WASM Support: Can be compiled to WebAssembly for browser usage

Usage

Basic Multisig Creation

use keymaster_multisig::*;

// Create public keys
let public_keys = vec![
    PublicKey::new(vec![0x02; 33]),
    PublicKey::new(vec![0x03; 33]),
    PublicKey::new(vec![0x04; 33]),
];

// Create private keys
let private_keys = vec![
    PrivateKey::new(vec![0x01; 32]),
    PrivateKey::new(vec![0x02; 32]),
];

// Create 2-of-3 multisig
let multisig = Multisig::new(
    Some(private_keys),
    public_keys,
    2
).unwrap();

Generate Locking Script

// Generate the multi-signature locking script
let script = multisig.lock().unwrap();
println!("Locking script: {}", hex::encode(&script));

Sign Transactions

// Create a transaction
let tx = Transaction::new(
    1,
    vec![TransactionInput::new("a".repeat(64), 0, 0xffffffff)],
    vec![TransactionOutput::new(1000, vec![...])],
    0,
);

// Sign the transaction
let signatures = multisig.sign(&tx, 0).unwrap();

Generate Single Signature

let signature = multisig.sign_one(&tx, 0, &private_keys[0]).unwrap();

Estimate Script Length

let estimated_length = multisig.estimate_length();
println!("Estimated unlocking script length: {} bytes", estimated_length);

Build Signature Script

let signatures = vec![sig1, sig2];
let script = multisig.build_sign_script(&signatures).unwrap();

WebAssembly Usage

The library can be compiled to WebAssembly for use in browsers:

import init, { MultisigWasm, create_locking_script } from './pkg/keymaster_multisig.js';

await init();

const publicKeys = [
    new Uint8Array([0x02, 0x02, 0x02, ...]),
    new Uint8Array([0x03, 0x03, 0x03, ...]),
];

const privateKeys = [
    new Uint8Array([0x01, 0x01, 0x01, ...]),
    new Uint8Array([0x02, 0x02, 0x02, ...]),
];

const multisig = new MultisigWasm(privateKeys, publicKeys, 2);
const lockingScript = multisig.lock();

Cross-Validation

This Rust implementation is designed to be fully compatible with the TypeScript and Golang implementations. The library produces identical outputs for:

• Locking scripts (P2MS format)
• Signature generation
• Script length estimation
• Signature script construction

Running Cross-Validation Tests

cargo test cross_validation

Building

Native Rust

cargo build

WebAssembly

wasm-pack build --target web

Testing

Run all tests:

cargo test

Run specific test suites:

cargo test lib_test
cargo test cross_validation

API Reference

Multisig

The main struct for creating and managing multi-signature operations.

Constructor

Multisig::new(
    private_keys: Option<Vec<PrivateKey>>,
    public_keys: Vec<PublicKey>,
    m: usize
) -> Result<Self, MultisigError>

Methods

• lock() -> Result<Vec<u8>, MultisigError>: Generate locking script
• sign(tx: &Transaction, input_index: usize) -> Result<Vec<Vec<u8>>, MultisigError>: Sign transaction
• sign_one(tx: &Transaction, input_index: usize, private_key: &PrivateKey) -> Result<Vec<u8>, MultisigError>: Generate single signature
• estimate_length() -> usize: Estimate unlocking script length
• create_fake_sign() -> Result<Vec<u8>, MultisigError>: Create fake signature for estimation
• build_sign_script(signatures: &[Vec<u8>]) -> Result<Vec<u8>, MultisigError>: Build signature script
• get_m() -> usize: Get required signature count
• get_n() -> usize: Get total public key count
• get_sig_hash_type() -> u8: Get signature hash type

Error Types

• InvalidPublicKeys: Invalid number of public keys
• NoPrivateKeys: Private keys not supplied when required
• InvalidM: Invalid m value (must be between 1 and n)
• EmptyPreviousTx: Previous transaction is empty
• SignatureError: Error during signature generation
• TransactionError: Invalid transaction data

Dependencies

• wasm-bindgen: For WebAssembly support
• serde: For serialization/deserialization
• serde-wasm-bindgen: For WASM-specific serde integration
• thiserror: For error handling
• hex: For hexadecimal encoding/decoding

License

MIT License

Contributing

Contributions are welcome! Please ensure all tests pass before submitting pull requests.