Multi-Chain Transaction Signing Demo

This repository contains a demo application that demonstrates the process of signing transactions on multiple blockchain networks using a single NEAR account. The application supports signing transactions on Ethereum (ETH), Binance Smart Chain (BNB), and Bitcoin (BTC) testnets.

Features

Sign transactions on ETH, BNB, and BTC testnets using a NEAR account
Derive addresses for each supported chain based on a derivation path
Check account balances on each supported chain
Send transactions on each supported chain

Prerequisites

Node.js
NPM package manager
A NEAR testnet account - Instructions to create an account: https://docs.near.org/tools/near-cli

Setup

Clone the repository:

Install the dependencies:

npm i

Set up the environment variables: Create a .env file in the root directory of the project and add the following variables:

NEXT_PUBLIC_NEAR_ACCOUNT_ID=your-near-testnet-account-id
NEXT_PUBLIC_NEAR_PRIVATE_KEY=your-near-testnet-private-key

Replace your-near-testnet-account-id with your NEAR testnet account ID and your-near-testnet-private-key with your NEAR testnet private key.

Running the Application

To start the development server, run the following command:

npm run dev

Open your browser and navigate to http://localhost:3000/multi-chain to access the application.

Usage

Select the desired chain (ETH, BNB, or BTC) from the dropdown menu.
Enter the derivation path for the selected chain.
Click the "Check Balance" button to fetch the account balance on the selected chain.
Enter the recipient's address in the "Address" field.
Enter the amount to send in the "Value" field.
Click the "Send Transaction" button to initiate the transaction.

Code Structure

The main components of the application are located in the following files:

pages/index.tsx: The main page of the application that handles user interactions and state management.
utils/chain/EVM.ts: Contains the EVM class that provides functions for interacting with Ethereum and Binance Smart Chain.
utils/chain/Bitcoin.ts: Contains the Bitcoin class that provides functions for interacting with the Bitcoin testnet.
utils/contract/signer.ts: Contains functions for signing transactions using the smart contract.
utils/kdf.ts: Contains functions for key derivation.