code: function safeRandom(len) {
      var randomBytes = new Uint8Array(len);
      while (len > 0) {
          var segmentSize = len % maxRandomQuota;
          segmentSize = segmentSize > 0 ? segmentSize : maxRandomQuota;
          var randomBytesSegment = new Uint8Array(segmentSize);
          webCrypto.getRandomValues(randomBytesSegment);
          len -= segmentSize;
          randomBytes.set(randomBytesSegment, len);
      }
      return randomBytes;
  }
docs: Gets random bytes from the CryptoEngine
  @param {number} len - bytes count
  @return {Uint8Array} - random bytes