javascript - 初学者如何用简单的方法破译铁栅栏密码？

Question

这是加密的代码。首先设置每隔一个字母，然后设置每隔一个字母（输入：abcdefgh；输出：acegdfh）。我无法弄清楚解密。我想，将加密文本一分为二并交替取一封信是可行的。对代码有什么想法吗？

onEvent("button_encrypt", "click", function(encrypt) {
  var text = getText("text_input1"); 
  var encripted = "";
  var i = 0;
  while ((i < klartext.length)) {
    encrypted = encrypted + text.charAt(i);
    i = i + 2;
  }
  i = 1;
  while ((i < text.length)) {
    encrypted = encrypted + text.charAt(i);
    i = i + 2;
  }
  setText("text_input1", encrypted); 
});

Answer 1

我喜欢这种加密风格。我在Code.org 应用程序中模拟了解决方案以进行测试等。

加密 首先我清理了一点加密代码。我发现几个变量名稍微有点不对劲。

onEvent("button_encrypt", "click", function(encrypt) {
  var text = getText("text_input1"); 
  var encrypted = "";
  
  var i = 0;
  while (i < text.length) {
    encrypted = encrypted + text.charAt(i);
    i = i + 2;
  }
  
  i = 1;
  while (i < text.length) {
    encrypted = encrypted + text.charAt(i);
    i = i + 2;
  }
  //changed ID, do to design
  setText("resultLbl", encrypted); 
});

解密 我通过获取加密数据，将其分成两半，然后将前面的字母从每一半剥离，来回交替来解决解密问题。

onEvent("decryptBtn", "click", function(){
  var text = getText("text_input1"); 
  var decrypt = "";
  
  //break message in half
  var half1 = text.substring(0,text.length/2);
  var half2 = text.substring(text.length/2);

  //Loop through two variables. If one is longer will always be half1.
  //Could do this with two index variables, but I did it by shrinking words
  while(half1.length > 0){
    //add to solution
    decrypt = decrypt + half1.substring(0,1);
    //cut the letter off the encrypted string once used
    half1 = half1.substring(1);
    
    //Repeat for half2
    //If protects from edge case of one more letter in half1
    if(half2.length > 0){
      decrypt = decrypt + half2.substring(0,1);
      half2 = half2.substring(1);
    }
  }
  
  setText("resultLbl", decrypt);
});