title: Python crypt/decrypt strings
body: <p>Is there a lib for this kind of crypt/decrypt in python? I am trying to generate encrypted ascii text which changes on each generation.</p>
  
  <p>If no lib for this, would you please advice a working alternative. Already tried to convert this PHP code to python but I failed.</p>
  
  <p>PHP what I use at the moment:</p>
  
  <pre><code>function keyED($txt,$encrypt_key)
  {
      $ctr=0;
      $tmp = "";
      $txt_len=strlen($txt);
      for ($i=0;$i&lt;$txt_len;$i++)
      {
          if ($ctr==strlen($encrypt_key)) $ctr=0;
          $tmp.= substr($txt,$i,1) ^ substr($encrypt_key,$ctr,1);
          $ctr++;
      }
      return $tmp;
  }
  
  function encrypt($txt,$key)
  {
      srand((double)microtime()*1000000);
      $encrypt_key = md5(rand(0,32000));
      $ctr = 0;
      $tmp = "";
      $txt_len = strlen($txt);
      for ($i=0;$i &lt; $txt_len;$i++)
      {
          if ($ctr==strlen($encrypt_key)) $ctr=0;
          $tmp.= substr($encrypt_key,$ctr,1) . (substr($txt,$i,1) ^ substr($encrypt_key,$ctr,1));
          $ctr++;
      }
      return keyED($tmp,$key);
  }
  
  function decrypt($txt,$key)
  {
      $txt = keyED($txt,$key);
      $tmp = "";
      $txt_len=strlen($txt);
      for ($i=0;$i&lt;$txt_len;$i++)
      {
          $md5 = substr($txt,$i,1);
          $i++;
          $tmp.= (substr($txt,$i,1) ^ $md5);
      }
      return $tmp;
  }
  
  $x = encrypt("test", "123");
  echo decrypt($x, "123") // -&gt; "test"
  </code></pre>