Derive btc segwit xpub from Ledger Nano

ledger_btc_segwit_xpub

import '@babel/polyfill'

import bitcoin from 'bitcoinjs-lib'
import bs58check from 'bs58check'

import Bitcoin from '@ledgerhq/hw-app-btc'
import Transport from '@ledgerhq/hw-transport-u2f'

const getCompressPublicKey = (publicKey) => {
    let compressedKeyIndex
    if (parseInt(publicKey.substring(128, 130), 16) % 2 !== 0) {
        compressedKeyIndex = '03'
    } else {
        compressedKeyIndex = '02'
    }
    const result = compressedKeyIndex + publicKey.substring(2, 66)
    return result
}

const createXpub = ({
    depth,
    fingerprint,
    childnum,
    chainCode,
    publicKey,
    network,
}) => {
    const array = [
        network.toString(16).padStart(8, '0'),
        depth.toString(16).padStart(2, '0'),
        fingerprint.toString(16).padStart(8, '0'),
        childnum.toString(16).padStart(8, '0'),
        chainCode,
        publicKey,
    ]

    return array.join('')
}

const getXpub58 = ({ node, account, fingerprint, network }) => {
    const { publicKey, chainCode } = node
    const compressPublicKey = getCompressPublicKey(publicKey)
    const childnum = (0x80000000 | account) >>> 0
    const xpub = createXpub({
        depth: 3,
        fingerprint,
        childnum,
        chainCode,
        publicKey: compressPublicKey,
        network,
    })

    const xpub58 = bs58check.encode(Buffer.from(parseHexString(xpub)))

    return xpub58
}

function parseHexString(str) {
    const result = []
    while (str.length >= 2) {
        result.push(parseInt(str.substring(0, 2), 16))
        str = str.substring(2, str.length)
    }
    return result
}

const getFingerprint = ({ publicKey }) => {
    let result = bitcoin.crypto.ripemd160(
        bitcoin.crypto.sha256(
            new Uint8Array(parseHexString(getCompressPublicKey(publicKey))),
        ),
    )

    return (
        ((result[0] << 24) |
            (result[1] << 16) |
            (result[2] << 8) |
            result[3]) >>>
        0
    )
}

const connect = async () => {
        try {
            const transport = await Transport.open(null)

            await transport.setExchangeTimeout(5000) // 5 seconds
            const btc = new Bitcoin(transport)

            const node = await btc.getWalletPublicKey("m/49'/0'/0'")
            const fingerprint = getFingerprint({ publicKey: node.publicKey })

            const xpub = getXpub58({
                node,
                fingerprint,
                account: 0,
                network: 0x0488b21e,
            })

            console.log('xpub:', xpub)
        } catch (err) {
            throw err
        }
}