Redeem Script Generator

Introduction

The Redeem Script Generator is a Node.js tool designed to facilitate the creation and verification of Bitcoin Pay-to-Script-Hash (P2SH) addresses using BIP-65. This project allows users to generate a redeem script and its corresponding P2SH address based on a given public key (in hexadecimal format) or a Taproot address and a specified block height. This tool is particularly useful for verifying the locking of assets in non-custodial staking setups, ensuring the security and immutability of transactions until a specified block height is reached.

Features

• Generate Redeem Script: Create a redeem script using a public key (hex) or a Taproot address and a block height.
• P2SH Address Verification: Verify and display the corresponding P2SH address of the generated redeem script.
• Support for BIP-65: Utilize the OP_CHECKLOCKTIMEVERIFY opcode to ensure time-locked transactions.
• Command-Line Interface: Simple and interactive CLI for user inputs.

Usage

Run the Script:

npm start

Follow the Prompts:

Enter a public key (hex) or a Taproot address. Enter the block height for the OP_CHECKLOCKTIMEVERIFY. Output:

The script will display the generated redeem script (in hex) and its corresponding P2SH address.

How It Works

Code Explanation

• Input Handling: The script uses readline to handle user inputs for the public key or Taproot address and the block height.
• Public Key Extraction: If a Taproot address is provided, the script extracts the internal public key using bitcoinjs-lib.
• Locking Script Creation: The getCltvRedeemScript function creates a locking script using OP_CHECKLOCKTIMEVERIFY and the provided public key.
• P2SH Address Calculation: The script calculates the corresponding P2SH address from the redeem script using bitcoinjs-lib.

Key Functions

• getCltvRedeemScript(pubkeyHex, blockheight): This function generates the redeem script for a given public key and block height using BIP-65.

function getCltvRedeemScript(pubkeyHex, blockheight) {
  const pubkey = Buffer.from(pubkeyHex, 'hex');
  const lockTime = bitcoin.script.number.encode(blockheight);
  const redeemScript = bitcoin.script.compile([
    lockTime,
    bitcoin.opcodes.OP_CHECKLOCKTIMEVERIFY,
    bitcoin.opcodes.OP_DROP,
    pubkey,
    bitcoin.opcodes.OP_CHECKSIG,
  ]);
  return redeemScript;
}

Benefits

• Non-Custodial Staking: This tool supports the BRC-H7LC standard, enabling users to lock their assets securely without relying on a third party.
• Script Verification: Users can verify the integrity and correctness of their redeem scripts and corresponding P2SH addresses.
• Educational Resource: This project serves as a practical example of implementing BIP-65 in a real-world application.

Resources and Further Reading:

• General BIPs: Visit the GitHub page for BIPs (Bitcoin Improvement Proposals)

• BIP 65 (OP_CHECKLOCKTIMEVERIFY): Read about BIP 65 on GitHub

• BIP 112 (CHECKSEQUENCEVERIFY): Discover the specifics of BIP 112 on GitHub

• HTLC (Hash Time-Locked Contracts): Explore how HTLCs function at Bitcoin Optech

• BRC-H7LC: A native Bitcoin staking, non-custodial for BRC20 Standard