Méthode et exemple d'analyse de la mise en œuvre du cryptage et du déchiffrement DES en PHP

<?php
$key = &#39;very important data&#39;;
function jiami($key, $str)
{
  /* Open module, and create IV */
  $td = mcrypt_module_open(&#39;des&#39;, &#39;&#39;, &#39;ecb&#39;, &#39;&#39;);
  //$td = mcrypt_module_open(MCRYPT_DES, &#39;&#39;, MCRYPT_MODE_CBC, &#39;&#39;);
  //$td = mcrypt_module_open(&#39;des&#39;, &#39;&#39;, &#39;cbc&#39;, &#39;&#39;);
  $key = substr($key, 0, mcrypt_enc_get_key_size($td));
  $iv_size = mcrypt_enc_get_iv_size($td);
  $iv = mcrypt_create_iv($iv_size, MCRYPT_RAND);
  /* Initialize encryption handle */
  if (mcrypt_generic_init($td, $key, $iv) === -1)
  {
    return FALSE;
  }
  /* Encrypt data */
  $c_t = mcrypt_generic($td, $str);
  /* Clean up */
  mcrypt_generic_deinit($td);
  mcrypt_module_close($td);
  return $c_t;
}
function jiemi($key, $str)
{
  /* Open module, and create IV */
  $td = mcrypt_module_open(&#39;des&#39;, &#39;&#39;, &#39;ecb&#39;, &#39;&#39;);
  //$td = mcrypt_module_open(MCRYPT_DES, &#39;&#39;, MCRYPT_MODE_CBC, &#39;&#39;);
  //$td = mcrypt_module_open(&#39;des&#39;, &#39;&#39;, &#39;cbc&#39;, &#39;&#39;);
  $key = substr($key, 0, mcrypt_enc_get_key_size($td));
  $iv_size = mcrypt_enc_get_iv_size($td);
  $iv = mcrypt_create_iv($iv_size, MCRYPT_RAND);
  /* Initialize encryption handle */
  if (mcrypt_generic_init($td, $key, $iv) === -1)
  {
    return FALSE;
  }
  /* Reinitialize buffers for decryption */
  $p_t = mdecrypt_generic($td, $str);
  /* Clean up */
  mcrypt_generic_deinit($td);
  mcrypt_module_close($td);
  return trim($p_t);
}
$str = &#39;hello world!&#39;;
echo &#39;key:&#39; . $key . &#39;<br>&#39;;
echo &#39;str:&#39; . $str . &#39;<br>&#39;;
$jiami = jiami($key, $str);
echo &#39;加密:&#39; . $jiami . &#39;<br>&#39;;
file_put_contents(&#39;jiamiqian.txt&#39;, $str);
file_put_contents(&#39;jiamihou.txt&#39;, $jiami);
$jiemi = jiemi($key, $jiami);
echo &#39;解密:&#39; . $jiemi . &#39;<br>&#39;;