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GFSJ0627积分 2金币 2

91最佳Writeup由 Robert_Wei 提供

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难度：2

方向：Web

题解数：108

解出人数：10185

题目来源: CTF

题目描述:

解密

题目场景:

http://61.147.171.105:56591

100%

倒计时: 3时59分18秒

<?php
$miwen="a1zLbgQsCESEIqRLwuQAyMwLyq2L5VwBxqGA3RQAyumZ0tmMvSGM2ZwB4tws";

function encode($str){
   $_o=strrev($str);
   // echo $_o;
       
   for($_0=0;$_0<strlen($_o);$_0++){
       
       $_c=substr($_o,$_0,1);
       $__=ord($_c)+1;
       $_c=chr($__);
       $_=$_.$_c;    
   }  
   return str_rot13(strrev(base64_encode($_)));
}

highlight_file(__FILE__);
/*
  逆向加密算法，解密$miwen就是flag
*/
?>

get the flag

`

<?php
$miwen="a1zLbgQsCESEIqRLwuQAyMwLyq2L5VwBxqGA3RQAyumZ0tmMvSGM2ZwB4tws";
echo $miwen;
function encode($str){
   $_o=strrev($str);
   echo $_o;
       
   for($_0=0;$_0<strlen($_o);$_0++){
       
       $_c=substr($_o,$_0,1);
       $__=ord($_c)+1;
       $_c=chr($__);
       $_=$_.$_c;    
   }  
   return str_rot13(strrev(base64_encode($_)));
}

//highlight_file(__FILE__);
/*
  逆向加密算法，解密$miwen就是flag
*/
echo "\n";
echo "test:";
echo encode("123");
$str = "Uryyb Jbeyq!";
   $str_rot13 = str_rot13($str);
   echo "\n";
   echo $str_rot13; // 输出 "Hello World!"

echo "\n";
echo str_rot13($miwen);
echo "\n";
echo strrev(str_rot13($miwen));
echo "\n";
echo base64_decode(  strrev(str_rot13($miwen)) );

$_o=base64_decode(  strrev(str_rot13($miwen)) );

for($_0=0;$_0<strlen($_o);$_0++){
       
   $_c=substr($_o,$_0,1);
   $__=ord($_c)-1;
   $_c=chr($__);
   $_=$_.$_c;    
}

echo "\n";
echo $_;
echo "\n";
echo strrev($_);


?>

`

using vscode

a1zLbgQsCESEIqRLwuQAyMwLyq2L5VwBxqGA3RQAyumZ0tmMvSGM2ZwB4tws
test:321lZQA
Hello World!
n1mYotDfPRFRVdEYjhDNlZjYld2Y5IjOkdTN3EDNlhzM0gzZiFTZ2MjO4gjf
fjg4OjM2ZTFiZzg0MzhlNDE3NTdkOjI5Y2dlYjZlNDhjYEdVRFRPfDtoYm1n
~88:36e1bg8438e41757d:29cgeb6e48c`GUDTO|;hbmg
}77925d0af7327d30646c918bfda5d37b_FTCSN{:galf
flag:{NSCTF_b73d5adfb819c64603d7237fa0d52977}