Practical PHP with public key encryption class sharing (the encryption result is different every time), PHP encryption_PHP tutorial

<&#63;php
/**
 * PHP加密类
 * 琼台博客
 */
class Jiami{
  // 公钥
  protected $key = 'lee'; 
  private function keyED($txt,$encrypt_key){
    $encrypt_key = md5($encrypt_key);
    $ctr=0;
    $tmp = '';
    for ($i=0;$i<strlen($txt);$i++){
      if ($ctr==strlen($encrypt_key)){
        $ctr=0;
      }
      $tmp.= substr($txt,$i,1) ^ substr($encrypt_key,$ctr,1);
      $ctr++;
    }
    return $tmp;
  }
 
  public function encrypt($txt,$key=''){
    if(empty($key)){
      $key=$this->key;
    }
    srand((double)microtime()*1000000);
    $encrypt_key = md5(rand(0,32000));
    $ctr=0;
    $tmp = '';
    for ($i=0;$i<strlen($txt);$i++) {
      if ($ctr==strlen($encrypt_key)){
        $ctr=0;
      }
      $tmp.= substr($encrypt_key,$ctr,1).(substr($txt,$i,1) ^ substr($encrypt_key,$ctr,1));
      $ctr++;
    }
    return $this->keyED($tmp,$key);
  }
 
  public function decrypt($txt,$key=''){
    if(empty($key)){
      $key=$this->key;
    }
 
    $txt = $this->keyED($txt,$key);
    $tmp = '';
    for ($i=0;$i<strlen($txt);$i++){
      $md5 = substr($txt,$i,1);
      $i++;
      $tmp.= (substr($txt,$i,1) ^ $md5);
    }
    return $tmp;
  }
 
  public function setKey($key){
    if(empty($key)){
      return null;
    }
    $this->key=$key;
  }
 
  public function getPK(){
    return $this->key;
  }
 
}

<&#63;php
// 先包含加密类
require_once('jiami.class.php');
 
// 要加密的字符串
$string = 'http://www.bkjia.com';
 
// 实例化加密类
$jiami= new Jiami();
 
// 设置公钥
$jiami->setKey('qttc');
 
// 加密字符串
$enc = $jiami->encrypt($string,$jiami->getPK());
 
// 解密字符串
$dec = $jiami->decrypt($enc,$jiami->getPK());
 
echo '<meta charset="utf-8" />';
echo '加密前 : '.$string .'<br/>';
echo '加密后 : '.$enc .'<br/>';
echo '解密后 : '.$dec;
&#63;>