PHP加密解密类实例分析

/*
 * -工具库-加密解密码
*/
class ption
{
 private static $original = array('=', '+', '/');
 private static $later = array('o0o0o', 'o0o0o', 'oo00o');
 function __construct()
 {
 }
 private static function md5($skey = '')
 {
  $skey = $skey ? $skey : 'ui' ; //uicms::_config('security/authkey');
  return md5(substr($skey, 0, 16));
 }
 /**
 * @use ption::en($string, $key);
 * @param string $string 需要加密的字串
 * @param string $skey 密钥
 * @param int $expiry 密文有效期, 加密时候有效， 单位 秒，0 为永久有效
 * @return string
 */
 static public function en($string = '', $skey = '', $expiry=0)
 {   
  if( is_array( $string ) )
  {
   $string = json_encode($string); // uicms::json($string, true, 'en');
  }     
  $string = str_pad($expiry ? $expiry + time : 0, 10, 0).$string;  
  $strarr = str_split(base64_encode($string));
  $strcount = count($strarr);  
  $skey = static::md5($skey);  
  foreach (str_split($skey) as $key => $value)
  {
   $key < $strcount && $strarr[$key].=$value;
  }
  return str_replace(self::$original, self::$later, join('', $strarr));
 }
 /**
 * @use ption::de($string, $key);
 * @param string $string 需要解密的字串
 * @param string $skey 密钥
 * @return string
 */
 static public function de($string = '', $skey = '')
 {   
  $strarr = str_split(str_replace(self::$later,self::$original,$string),2);
  $strcount = count($strarr);
  $skey = static::md5($skey);
  foreach (str_split($skey) as $key => $value)
  {
   $key < $strcount && $strarr[$key][1] === $value && $strarr[$key] = $strarr[$key][0];
  }   
  $result = base64_decode(join('', $strarr));
  if(substr($result, 0, 10) == 0 || substr($result, 0, 10) - time > 0)
  {
   return substr($result, 10);
  }
  else
  {
   return false;
  }   
 }  
}

$str['username'] = 'oschina';
$str['pw'] = '123456';
$str['huoxin'] = '!@#$%^&';
echo "string : " . $str . " <br />";
echo "encode : " . ($enstring = ption::en($str)) . '<br />';
echo "decode : " . ption::de($enstring);