初學者如何用簡單的方法破譯圍欄密碼？

Question

這是加密的代碼。 首先設置每隔一個字母，然后每隔一個字母（輸入：abcdefgh；輸出：acegdfh）。 我無法弄清楚解密。 我想，將加密文本一分為二，然后交替地從每個文本中取出一封信是可行的。 對代碼有什么想法嗎？

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

我喜歡這種加密風格。 我在Code.org 應用程序中模擬了解決方案以進行測試等。

加密首先我稍微清理了加密代碼。 我發現了一些稍微偏離的變量名稱。

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); 
});

解密我通過將加密數據分成兩半，然后從每一半上撕下前面的字母，來回交替來解決解密問題。

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);
});