var characters = [0x57, 0x65, 0x6c, 0x63, 0x6f, 0x6d, 0x65, 0x20, 0x74, 0x6f, 0x20, 0x47, 0x43, 0x48, 0x51] ;

var message = "";

characters.forEach((char, index) => {
  message += String. fromCharCode(char);
});
alert (message);

// Message 2
function decode(encoded_text, key) {
  var plaintext;
  for (var i = 0; i < encoded_text.length; i++) {
    var encoded_byte = encoded_text[i].charCodeAt (0) ;
    var key_byte = key[i % key.length].charCodeAt(0) ;

    plaintext += String. fromCharCode (encoded_byte ^ key_byte) ;
  }
return plaintext;
}

var encoded_text = "gNSkYr+VqyGl1Lhko8fqYq7UpGajiuo67w==";
var key = "\xc6\xb5\xca\x01";
var base64_decode = atob;

alert (decode(base64_decode(encoded_text), key)) ;