code: function verifyHeaders(headers) {
    for (let i = 0; i < headers.length; i++) {
      if (!/^([^\s:]|[^\s:][^:]*[^\s:]): .+$/.test(headers[i])) {
        throw new Error('Improperly formatted armor header: ' + headers[i]);
      }
      if (!/^(Version|Comment|MessageID|Hash|Charset): .+$/.test(headers[i])) {
        util.print_debug_error(new Error('Unknown header: ' + headers[i]));
      }
    }
  }
docs: Verify armored headers. RFC4880, section 6.3: "OpenPGP should consider improperly formatted
  Armor Headers to be corruption of the ASCII Armor."
  @private
  @param  {Array<String>} headers Armor headers