简单有key的加密解密算法

 1 define(‘KEY‘, ‘123456‘);
 2 $data = ‘oehpetyFTdYwZ3frZi1KkgtizgQs‘;        // 被加密信息  
 3 $encrypt = encrypt($data);  
 4 $decrypt = decrypt($encrypt);  
 5 echo $encrypt, "\n", $decrypt;  
 6 function decrypt($data) {
 7     $key = md5(KEY);
 8     $x = 0;
 9     $data = base64_decode($data);
10     $len = strlen($data);
11     $l = strlen($key);
12     $char = $str = ‘‘;
13     for ($i = 0; $i < $len; $i++) {
14         if ($x == $l) {
15             $x = 0;
16         }
17         $char .= substr($key, $x, 1);
18         $x++;
19     }
20     for ($i = 0; $i < $len; $i++) {
21         if (ord(substr($data, $i, 1)) < ord(substr($char, $i, 1))) {
22             $str .= chr((ord(substr($data, $i, 1)) + 256) - ord(substr($char, $i, 1)));
23         } else {
24             $str .= chr(ord(substr($data, $i, 1)) - ord(substr($char, $i, 1)));
25         }
26     }
27     return $str;
28 }
29 
30 function encrypt($data) {
31     $key = md5(KEY);
32     $x = 0;
33     $len = strlen($data);
34     $l = strlen($key);
35     $char = $str = ‘‘;
36     for ($i = 0; $i < $len; $i++) {
37         if ($x == $l) {
38             $x = 0;
39         }
40         $char .= $key{$x};
41         $x++;
42     }
43     for ($i = 0; $i < $len; $i++) {
44         $str .= chr(ord($data{$i}) + (ord($char{$i})) % 256);
45     }
46     return base64_encode($str);
47 }