How to use the bitcoinjs-lib.crypto.sha256 function in bitcoinjs-lib

function makeLegacyAuthToken(challengeText: string, signerKeyHex: string): string {
  // only sign specific legacy auth challenges.
  let parsedChallenge
  try {
    parsedChallenge = JSON.parse(challengeText)
  } catch (err) {
    throw new Error('Failed in parsing legacy challenge text from the gaia hub.')
  }
  if (parsedChallenge[0] === 'gaiahub'
      && parsedChallenge[3] === 'blockstack_storage_please_sign') {
    const signer = hexStringToECPair(signerKeyHex
                                     + (signerKeyHex.length === 64 ? '01' : ''))
    const digest = bjsCrypto.sha256(Buffer.from(challengeText))

    const signatureBuffer = signer.sign(digest)
    const signatureWithHash = script.signature.encode(
      signatureBuffer, Transaction.SIGHASH_NONE)
    
    // We only want the DER encoding so remove the sighash version byte at the end.
    // See: https://github.com/bitcoinjs/bitcoinjs-lib/issues/1241#issuecomment-428062912
    const signature = signatureWithHash.toString('hex').slice(0, -2)
    
    const publickey = getPublicKeyFromPrivate(signerKeyHex)
    const token = Buffer.from(JSON.stringify(
      { publickey, signature }
    )).toString('base64')
    return token
  } else {
    throw new Error('Failed to connect to legacy gaia hub. If you operate this hub, please update.')

privatelyNamedChild(name) {
    if (name.length === 0) {
      throw new Error('Name must be at least one character long')
    }
    const entropy = hashing.sha256(
      Buffer.concat([
        this.privateKey(),
        new Buffer(name)
      ])
    )
    return this.child(entropy)
  }
}

profileComponents.map((data) => {
    const derivationEntropy = hashing.sha256(
      Buffer.concat([
        privateKeychain.privateKey(),
        new Buffer(JSON.stringify(data))
      ])
    )

    const privateChildKeychain = privateKeychain.child(derivationEntropy),
          privateKey = privateChildKeychain.privateKey('hex'),
          publicKey = privateChildKeychain.publicKeychain().publicKey('hex')

    const subject = {publicKey: publicKey}
    let token = signToken(data, privateKey, subject, null, signingAlgorithm),
        tokenRecord = wrapToken(token)
    tokenRecord.parentPublicKey = parentPublicKey
    tokenRecord.derivationEntropy = derivationEntropy.toString('hex')

publiclyNamedChild(name) {
    if (name.length === 0) {
      throw new Error('Name must be at least one character long')
    }
    const entropy = hashing.sha256(
      Buffer.concat([
        this.publicKey(),
        new Buffer(name)
      ])
    )
    return this.child(entropy)
  }
}

export function hash128(buff: Buffer) {
  return Buffer.from(bjsCrypto.sha256(buff).slice(0, 16))
}

export function hash160(buff: Buffer) {
  const sha256 = bjsCrypto.sha256(buff)
  return (new RIPEMD160()).update(sha256).digest()
}