一组PHP可逆加密解密算法

示例代码

<?php
header("Content-type:text/html;charset=utf-8");
error_reporting(E_ALL);


function encrypt($data, $key)
{
    $key    =    md5($key);
    $x      =    0;
    $len    =    strlen($data);
    $l      =    strlen($key);
	$char   =    '';
    for ($i = 0; $i < $len; $i++)
    {
        if ($x == $l) 
        {
            $x = 0;
        }
        $char .= $key{$x};
        $x++;
    }
	$str  =  '';
    for ($i = 0; $i < $len; $i++)
    {
        $str .= chr(ord($data{$i}) + (ord($char{$i})) % 256);
    }
    return base64_encode($str);
}

function decrypt($data, $key)
{
    $key = md5($key);
    $x = 0;
    $data = base64_decode($data);
    $len = strlen($data);
    $l = strlen($key);
	$char = '';
    for ($i = 0; $i < $len; $i++)
    {
        if ($x == $l) 
        {
            $x = 0;
        }
        $char .= substr($key, $x, 1);
        $x++;
    }
	$str = '';
    for ($i = 0; $i < $len; $i++)
    {
        if (ord(substr($data, $i, 1)) < ord(substr($char, $i, 1)))
        {
            $str .= chr((ord(substr($data, $i, 1)) + 256) - ord(substr($char, $i, 1)));
        }
        else
        {
            $str .= chr(ord(substr($data, $i, 1)) - ord(substr($char, $i, 1)));
        }
    }
    return $str;
}


$data = 'PHP加密解密算法';    // 被加密信息
$key  = '123';    // 密钥


$encrypt = encrypt($data, $key);
$decrypt = decrypt($encrypt, $key);
echo $encrypt, "
", $decrypt;

?>