Generating a bitcoin address

The sequence of steps to generate a bitcoin address are:

1. Generate a private key - A private key is a 32 bit number picked at random.
2. Generate the public key - Public key is calculated from private key using elliptic curve multiplication. Note: In bcoin, we can directly get the public key using the bcoin.HDPrivateKey.generate() method.
3. Generate the public key hash -
   • Hash the public key using SHA256 cryptographic hashing algorithm.
   • Hash the result with RIPEMD160 cryptographic hashing algorithm. The end result is the public key hash
4. Base58Check encoding -
   • Add version byte as prefix to the public key hash.
   • Generate the version byte hash by hashing the result with SHA256 cryptographic hashing algorithm twice.
   • Get the first four bytes of the version byte hash. This is the checksum.
   • Concatenate the checksum with the public key hash.
5. Encode the result in base58 encoding. The result is the base58 encoded bitcoin address and it always starts with ‘1’.

Code

"use strict"

const { base58 } = require("bstring")
const bcoin = require("bcoin")
const bcrypto = require("bcrypto")

// Generate public key using bcoin
const publicKey = bcoin.HDPrivateKey.generate().publicKey

// Generate publicKeyHash
const publicKeyHash = bcrypto.RIPEMD160.digest(bcrypto.SHA256.digest(publicKey))

// Base58 check encoding
const addressVersionByte = Buffer.concat([Buffer.alloc(1), publicKeyHash])
const addressVersionByteHash = bcrypto.SHA256.digest(
  bcrypto.SHA256.digest(addressVersionByte)
)

const checksum = addressVersionByteHash.slice(0, 4)

const address25Byte = Buffer.concat([addressVersionByte, checksum])

// Base58 encoded bitcoin address, starts with '1'
const addressBase58Encoded = base58.encode(address25Byte)

console.log(`Public key: ${publicKey.toString("hex")}`)
console.log(`Address: ${addressBase58Encoded}`)

Extract P2SH address from a pubKey script –>

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