//var ctext = rc4("我是明文","我是密碼");//var text = rc4(ctext, "我是密碼");function rc4(data, key) {  var seq = Array(256); //int  var das = Array(data.length); //code of data  for (var i = 0; i < 256; i++) {    seq[i] = i;    var j = (j + seq[i] + key.charCodeAt(i % key.length)) % 256;    var temp = seq[i];    seq[i] = seq[j];    seq[j] = temp;  }  for (var i = 0; i < data.length; i++) {    das[i] = data.charCodeAt(i)  }  for (var x = 0; x < das.length; x++) {    var i = (i + 1) % 256;    var j = (j + seq[i]) % 256;    var temp = seq[i];    seq[i] = seq[j];    seq[j] = temp;    var k = (seq[i] + (seq[j] % 256)) % 256;    das[x] = String.fromCharCode(das[x] ^ seq[k]);  }  return das.join('');}