Chainsig.js

A TypeScript library for creating transactions for different chains and signing them with NEAR's MPC (Multi-party Computation)service.

Overview

This library provides a unified interface for interacting with different blockchain networks through a common set of methods. It uses MPC for secure key management and transaction signing.

Features

• Multi-Chain Support: Built-in support for EVM chains, Bitcoin, Cosmos, Solana, Aptos, and SUI networks
• Unified Interface: Common API across all supported chains
• MPC Integration: Secure key management and transaction signing
• Type Safety: Full TypeScript support with comprehensive type definitions
• Modular Design: Easy to extend with new chain implementations
• Secure: No private keys stored or transmitted

Supported Chains

The library provides chain adapters for the following blockchain networks:

• EVM Chains: Ethereum, BSC, Polygon, Arbitrum, Optimism, and other EVM-compatible networks
• Bitcoin: Bitcoin mainnet and testnet with P2WPKH transaction support
• Cosmos: Cosmos Hub, Osmosis, and other Cosmos SDK-based chains
• Solana: High-performance blockchain with native token transfers
• Aptos: Move-based blockchain with Ed25519 signature support
• SUI: Move-based blockchain with Ed25519 signature support
• XRP Ledger: XRP mainnet, testnet, and devnet with native XRP transfers

Each chain adapter provides a unified interface for:

• Address and public key derivation
• Balance checking
• Transaction preparation and signing
• Transaction broadcasting

Installation

npm install chainsig.js
# or
yarn add chainsig.js
# or
pnpm add chainsig.js
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Docs and Examples

Examples for sending transfers and function calls with chainsig.js via a NEAR wallet can be found in the near-multichain repo, along with in depth documentation in the NEAR docs.

Examples for sending transfers with chainsig.js via near-api-js/near-js can be found in the examples folder.

Full typedocs for the library can be found here.

Using the Library

Because of underlying dependencies, this library is a Commonjs project. You may need to configure your projects to use this library.

Here are simple examples in TypeScript and JavaScript.

Quick Example

import { chainAdapters, contracts } from "chainsig.js";
import { KeyPair, type KeyPairString } from "@near-js/crypto";
import { createPublicClient, http } from "viem";
import { mainnet } from "viem/chains";

// Initialize NEAR connection with credentials from environment
const accountId = process.env.NEAR_ACCOUNT_ID;
const privateKey = process.env.NEAR_PRIVATE_KEY as KeyPairString;

if (!accountId || !privateKey) {
  throw new Error(
    "NEAR_ACCOUNT_ID and NEAR_PRIVATE_KEY must be set in environment",
  );
}

const keypair = KeyPair.fromString(privateKey);

const contract = new contracts.near.ChainSignatureContract({
  networkId: "testnet",
  contractId: "v1.signer-prod.testnet",
  accountId,
  keypair,
});

const publicClient = createPublicClient({
  chain: mainnet,
  transport: http(),
});

const evmChain = new chainAdapters.evm.EVM({
  publicClient,
  contract,
});

// Derive address and public key
const { address, publicKey } = await evmChain.deriveAddressAndPublicKey(
  accountId,
  "any_string",
);

// Check balance
const { balance, decimals } = await evmChain.getBalance(address);

// Create and sign transaction
const { transaction, hashesToSign } =
  await evmChain.prepareTransactionForSigning({
    from: "0x...",
    to: "0x...",
    value: 1n,
  });

// Sign with MPC
const signature = await contract.sign({
  payload: hashesToSign[0].payload,
  path: "any_string",
  key_version: 0,
});

// Add signature
const signedTx = evmChain.finalizeTransactionSigning({
  transaction,
  rsvSignatures: [signature],
});

// Broadcast transaction
const txHash = await evmChain.broadcastTx(signedTx);
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