实验吧-杂项-你没有见过的加密！(php srand()和rand()函数)

什么垃圾东西，弄半天，Windows上运行乱码，linux上7.3的php运行也是乱码（气死）。

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<?php


	function encrypt($str)
	{
		$cryptedstr = "";
		srand(3284724);
		for ($i =0; $i < strlen($str); $i++)
		{
			$temp = ord(substr($str,$i,1)) ^ rand(0, 255);
			while(strlen($temp)<3)
			{
				$temp = "0".$temp;

			}
			$cryptedstr .= $temp. "";
		}
		return base64_encode($cryptedstr);
	}
	
?>

就顺着加密思路写解密代码：

<?php
$cryptedstr = "MDEzMjE5MDAyMTg0MTUzMjQwMTQ0MDc3MjUzMDk2MTc1MTUzMTE4MTg4MDEwMDA2MTg4MDA0MjM4MDI1MTA3MTU4MTc5MTM4";
$cryptedstr = base64_decode($cryptedstr);

$len = strlen($cryptedstr);
$str = "";
srand(3284724);
for($i=0;$i<$len/3;$i++){
	$temp = substr($cryptedstr, 0, 3);
	$cryptedstr = substr($cryptedstr, 3);
	$n = intval($temp)^rand(0, 255);
	$str .= chr($n);
}

echo "$str";



?>

气死了，最后在这里运行才拿到flag：http://www.dooccn.com/php/

知识点：1）srand()和rand()

参考：https://blog.csdn.net/zz_Caleb/article/details/87829463

2）substr()

参考：https://blog.csdn.net/zz_Caleb/article/details/87829892