CLASSE DE CHIFFREMENT DE DONNÉS AVEC MCRYPT

<?php
// Copyright (c) 2010 Rodolphe Breard
// 
// Permission to use, copy, modify, and/or distribute this software for any
// purpose with or without fee is hereby granted, provided that the above
// copyright notice and this permission notice appear in all copies.
// 
// THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
// WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
// MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
// ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
// WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
// ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
// OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
//

class			MyCrypt
{
  protected		$td;
  protected		$iv;
  protected		$key;

  public function	__construct(&$key)
  {
    $this->td = mcrypt_module_open(MCRYPT_RIJNDAEL_256, '', MCRYPT_MODE_ECB, '');
    if ($this->td === false)
      throw new Exception('MyCrypt::__construct: unable to open module');
    $this->iv = mcrypt_create_iv(mcrypt_enc_get_iv_size($this->td), MCRYPT_RAND);
    if ($this->iv === false)
      throw new Exception('MyCrypt::__construct: unable to create the initialization vector');
    $this->key = substr(hash('sha512', $key, true), 0, mcrypt_enc_get_key_size($this->td));
    $end = strlen($key);
    for ($i = 0; $i < $end; $i++)
      $key[$i] = "\0";
  }

  public function	__destruct()
  {
    $this->bzero($this->key);
    if (mcrypt_module_close($this->td) === false)
      throw new Exception('MyCrypt::__destruct: unable to close module');
  }

  public function	crypt(&$data)
  {
    return base64_encode($this->mcryptGeneric($data, 'mcrypt_generic'));
  }

  public function	decrypt(&$data)
  {
    $tmp = base64_decode($data);
    $this->bzero($data);
    return $this->mcryptGeneric($tmp, 'mdecrypt_generic');
  }

  public function	bzero(&$str)
  {
    $end = strlen($str);
    for ($i = 0; $i < $end; $i++)
      $str[$i] = "\0";
  }

  protected function	mcryptGeneric(&$data, $func)
  {
    $ret = '';
    try
      {
	$funcLst = array('mcrypt_generic', 'mdecrypt_generic');
	if (!in_array($func, $funcLst))
	  throw new Exception("MyCrypt::mcryptGeneric: $func: unknown function");
	$in = mcrypt_generic_init($this->td, $this->key, $this->iv);
	if ($in === false)
	  throw new Exception('MyCrypt::mcryptGeneric: init: incorrect parameters');
	elseif ($in == -3)
	  throw new Exception('MyCrypt::mcryptGeneric: init: incorrect key length');
	elseif ($in == -4)
	  throw new Exception('MyCrypt::mcryptGeneric: init: memory allocation problem');
	elseif ($in < 0)
	  throw new Exception('MyCrypt::mcryptGeneric: init: unknown error');
	$ret = $func($this->td, $data);
	if (mcrypt_generic_deinit($this->td) === false)
	  throw new Exception('MyCrypt::mcryptGeneric: unable to deinit');
      } 
    catch (Exception $e)
      {
	$this->bzero($data);
	throw $e;
      }
    $this->bzero($data);
    return $ret;
  }
}

?>