code: function(password, keyFile) {
      var that = this;
      this.ready = Promise.all([
          this.setPassword(password),
          this.setKeyFile(keyFile)
      ]).then(function() {
          return that;
      });
  }
docs: Credentials
  @param {ProtectedValue} password
  @param {String|ArrayBuffer|Uint8Array} [keyFile]
  @constructor