web2

GFSJ0627積分 2金幣 2

91最佳Writeup由 Robert_Wei 提供

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難度：2

方向：Web

題解數(shù)：108

解出人數(shù)：10185

題目來(lái)源: CTF

題目描述:

解密

題目場(chǎng)景:

http://61.147.171.105:56591

100%

倒計(jì)時(shí): 3時(shí)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; // 輸出 "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}