PHP加密解密类实例分析

/*
 * -工具库-加密解暗码
*/
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,16));
 }
 /**
 * @use ption::en($string,$key);
 * @param String $string 需要加密的字串
 * @param String $skey 密钥
 * @param int $expiry 密文有效期,0 为永久有效
 * @return String
 */
 static public function en($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($result,10) == 0 || substr($result,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);