mirall-cli / node_modules / bare-crypto / lib / hmac.js

const { Transform } = require('bare-stream')
const assert = require('bare-assert')
const binding = require('../binding')
const constants = require('./constants')

module.exports = class CryptoHmac extends Transform {
  constructor(algorithm, key, opts = {}) {
    super(opts)

    const { encoding = 'utf8' } = opts

    if (typeof key === 'string') key = Buffer.from(key, encoding)

    assert(ArrayBuffer.isView(key))

    this._finalized = false

    binding.hmacInit(this, constants.toHash(algorithm), key.buffer, key.byteOffset, key.byteLength)
  }

  update(data, encoding = 'utf8') {
    if (this._finalized) {
      throw new Error('Hmac has already been finalized')
    }

    if (typeof data === 'string') data = Buffer.from(data, encoding)

    assert(ArrayBuffer.isView(data))

    binding.hmacUpdate(this, data.buffer, data.byteOffset, data.byteLength)

    return this
  }

  digest(encoding) {
    if (this._finalized) {
      throw new Error('Hmac has already been finalized')
    }

    const digest = Buffer.from(binding.hmacFinal(this))
    this._finalized = true

    return encoding && encoding !== 'buffer' ? digest.toString(encoding) : digest
  }

  _transform(data, encoding, cb) {
    this.update(data)

    cb(null)
  }

  _flush(cb) {
    this.push(this.digest())

    cb(null)
  }
}