實驗吧-NSCTF web200

直接寫個php腳本跑

<?php
$str="a1zLbgQsCESEIqRLwuQAyMwLyq2L5VwBxqGA3RQAyumZ0tmMvSGM2ZwB4tws";
$_="";
$_o = base64_decode(strrev(str_rot13($str)));
for($_0=0;$_0<strlen($_o);$_0++){
	$_c=substr($_o,$_0,1);
	$__=ord($_c)-1;
	$_c=chr($__);
	$_=$_.$_c;
}
$_=strrev($_);
echo $_;
?>

得到flag：

flag:{NSCTF_b73d5adfb819c64603d7237fa0d52977}