PHP模拟百度URL加密解密算法

PHP模拟百度URL加密解密算法的代码如下

<?php
$time = time() . rand(1000, 9999);
$data = "{$time}###https://www.lseventt.net"; // 被加密信息
$key = '123'; // 密钥
$encrypt = encrypt($data, $key);
$decrypt = decrypt($encrypt, $key);
echo $encrypt, "\n", $decrypt;
function encrypt($data, $key) {
    $key = md5($key);
    $x = 0;
    $len = strlen($data);
    $l = strlen($key);
    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);
}
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;
}