PHP可逆加密

<?php
//加密算法
function encrypt($data, $key)
{
$key = md5($key);
$x = 0;
$len = strlen($data);
$l = strlen($key);
$char = $str = ‘‘;
for ($i = 0; $i < $len; $i++)
{
if ($x == $l)
{
$x = 0;
}
$char .= $key{$x};
$x++;
}
for ($i = 0; $i < $len; $i++)
{
$str .= chr(ord($data{$i}) + (ord($char{$i})) % 256);
}
return base64_encode($str);
}
//解密算法

function decrypt($data, $key)
{
$key = md5($key);
$x = 0;
$data = base64_decode($data);
$len = strlen($data);
$l = strlen($key);
for ($i = 0; $i < $len; $i++)
{
if ($x == $l)
{
$x = 0;
}
$char .= substr($key, $x, 1);
$x++;
}
for ($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;
}

//__maim__

$data = ‘向翔招商卡号112233445566‘; // 被加密信息
$key = ‘zlf‘; // 密钥
$encrypt = encrypt($data, $key);
$decrypt = decrypt($encrypt, $key);
echo $encrypt, "<br/>", $decrypt;

?>

原文：http://www.cnblogs.com/b13272012771/p/3977717.html