function base64ToBuf(b64) {
  var binStr = atob(b64)
  var len = binStr.length
  var arr = new Uint8Array(len)
  for (var i = 0; i < len; i++) {
    arr[i] = binStr.charCodeAt(i)
  }
  return arr
}
JSON text exchanged between systems that are not part of a closed ecosystem
MUST be encoded using UTF-8.

{@link https://tools.ietf.org/html/rfc8259#section-8.1 | Character Encoding}