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node_modules/pbkdf2/lib/async.js 2.61 KB
aaac7fed   liuqimichale   add
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  var checkParameters = require('./precondition')
  var defaultEncoding = require('./default-encoding')
  var sync = require('./sync')
  var Buffer = require('safe-buffer').Buffer
  
  var ZERO_BUF
  var subtle = global.crypto && global.crypto.subtle
  var toBrowser = {
    'sha': 'SHA-1',
    'sha-1': 'SHA-1',
    'sha1': 'SHA-1',
    'sha256': 'SHA-256',
    'sha-256': 'SHA-256',
    'sha384': 'SHA-384',
    'sha-384': 'SHA-384',
    'sha-512': 'SHA-512',
    'sha512': 'SHA-512'
  }
  var checks = []
  function checkNative (algo) {
    if (global.process && !global.process.browser) {
      return Promise.resolve(false)
    }
    if (!subtle || !subtle.importKey || !subtle.deriveBits) {
      return Promise.resolve(false)
    }
    if (checks[algo] !== undefined) {
      return checks[algo]
    }
    ZERO_BUF = ZERO_BUF || Buffer.alloc(8)
    var prom = browserPbkdf2(ZERO_BUF, ZERO_BUF, 10, 128, algo)
      .then(function () {
        return true
      }).catch(function () {
        return false
      })
    checks[algo] = prom
    return prom
  }
  
  function browserPbkdf2 (password, salt, iterations, length, algo) {
    return subtle.importKey(
      'raw', password, {name: 'PBKDF2'}, false, ['deriveBits']
    ).then(function (key) {
      return subtle.deriveBits({
        name: 'PBKDF2',
        salt: salt,
        iterations: iterations,
        hash: {
          name: algo
        }
      }, key, length << 3)
    }).then(function (res) {
      return Buffer.from(res)
    })
  }
  
  function resolvePromise (promise, callback) {
    promise.then(function (out) {
      process.nextTick(function () {
        callback(null, out)
      })
    }, function (e) {
      process.nextTick(function () {
        callback(e)
      })
    })
  }
  module.exports = function (password, salt, iterations, keylen, digest, callback) {
    if (typeof digest === 'function') {
      callback = digest
      digest = undefined
    }
  
    digest = digest || 'sha1'
    var algo = toBrowser[digest.toLowerCase()]
  
    if (!algo || typeof global.Promise !== 'function') {
      return process.nextTick(function () {
        var out
        try {
          out = sync(password, salt, iterations, keylen, digest)
        } catch (e) {
          return callback(e)
        }
        callback(null, out)
      })
    }
  
    checkParameters(password, salt, iterations, keylen)
    if (typeof callback !== 'function') throw new Error('No callback provided to pbkdf2')
    if (!Buffer.isBuffer(password)) password = Buffer.from(password, defaultEncoding)
    if (!Buffer.isBuffer(salt)) salt = Buffer.from(salt, defaultEncoding)
  
    resolvePromise(checkNative(algo).then(function (resp) {
      if (resp) return browserPbkdf2(password, salt, iterations, keylen, algo)
  
      return sync(password, salt, iterations, keylen, digest)
    }), callback)
  }