$str = "测试加密解密";  $key = ‘^&yang*%#2014!$‘;  $new_str = my_encrypt($str, $key );  echo ‘原始:‘.$str.‘<br />‘;   echo ‘加密:‘.$new_str.‘<br />‘;  echo ‘解密:‘.my_decrypt($new_str, $key);    function my_encrypt($string,    $key=‘‘)  {      $key = md5($key);      $key_length = strlen($key);      $string = substr(md5($string.$key),0,8).$string;      $string_length = strlen($string);      $rndkey = $box = array();      $result = ‘‘;      for($i=0; $i<=255; $i++)      {          $rndkey[$i] = ord($key[$i%$key_length]);          $box[$i] = $i;      }      for($j=$i=0; $i<256; $i++)      {          $j = ($j+$box[$i]+$rndkey[$i])%256;          $tmp = $box[$i];          $box[$i] = $box[$j];          $box[$j] = $tmp;      }      for($a=$j=$i=0; $i<$string_length; $i++)      {          $a = ($a+1)%256;          $j = ($j+$box[$a])%256;          $tmp = $box[$a];          $box[$a] = $box[$j];          $box[$j] = $tmp;          $result .= chr(ord($string[$i])^($box[($box[$a]+$box[$j])%256]));      }            return str_replace(‘=‘,‘‘,base64_encode($result));      } function my_decrypt($string, $key=‘‘)  {      $key = md5($key);      $key_length = strlen($key);      $string = base64_decode($string);      $string_length = strlen($string);      $rndkey = $box = array();      $result = ‘‘;      for($i=0; $i<=255; $i++)      {          $rndkey[$i] = ord($key[$i%$key_length]);          $box[$i] = $i;      }      for($j=$i=0; $i<256; $i++)      {          $j = ($j+$box[$i]+$rndkey[$i])%256;          $tmp = $box[$i];          $box[$i] = $box[$j];          $box[$j] = $tmp;      }      for($a=$j=$i=0; $i<$string_length; $i++)      {          $a = ($a+1)%256;          $j = ($j+$box[$a])%256;          $tmp = $box[$a];          $box[$a] = $box[$j];          $box[$j] = $tmp;          $result .= chr(ord($string[$i])^($box[($box[$a]+$box[$j])%256]));      }            if(substr($result,0,8) == substr(md5(substr($result,8).$key),0,8))      {          return substr($result,8);      }      else      {          return‘‘;      }  }