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                              mcrypt_module_open

   (PHP 4 >= 4.0.2)
   mcrypt_module_open -- Opens the module of the algorithm and the mode
   to be used

Description

   resource mcrypt_module_open ( string algorithm, string
   algorithm_directory, string mode, string mode_directory)

   This function opens the module of the algorithm and the mode to be
   used. The name of the algorithm is specified in algorithm, e.g.
   "twofish" or is one of the MCRYPT_ciphername constants. The module is
   closed by calling mcrypt_module_close(). Normally it returns an
   encryption descriptor, or FALSE on error.

   The algorithm_directory and mode_directory are used to locate the
   encryption modules. When you supply a directory name, it is used. When
   you set one of these to the empty string (""), the value set by the
   mcrypt.algorithms_dir or mcrypt.modes_dir ini-directive is used. When
   these are not set, the default directories that are used are the ones
   that were compiled in into libmcrypt (usually
   /usr/local/lib/libmcrypt).

   Example 1. mcrypt_module_open() examples
   <?php
       $td = mcrypt_module_open(MCRYPT_DES, '',
           MCRYPT_MODE_ECB, '/usr/lib/mcrypt-modes');
       $td = mcrypt_module_open('rijndael-256', '', 'ofb', '');
   ?>

   The first line in the example above will try to open the DES cipher
   from the default directory and the EBC mode from the directory
   /usr/lib/mcrypt-modes. The second example uses strings as name for the
   cipher an dmode, this only works when the extension is linked against
   libmcrypt 2.4.x or 2.5.x.

   Example 2. Using mcrypt_module_open() in encryption
   <?php
       /* Open the cipher */
       $td = mcrypt_module_open('rijndael-256', '', 'ofb', '');
       /* Create the IV and determine the keysize length */
       $iv = mcrypt_create_iv(mcrypt_enc_get_iv_size($td),
   MCRYPT_DEV_RANDOM);
       $ks = mcrypt_enc_get_key_size($td);
       /* Create key */
       $key = substr(md5('very secret key'), 0, $ks);
       /* Intialize encryption */
       mcrypt_generic_init($td, $key, $iv);
       /* Encrypt data */
       $encrypted = mcrypt_generic($td, 'This is very important data');
       /* Terminate encryption handler */
       mcrypt_generic_deinit($td);
       /* Initialize encryption module for decryption */
       mcrypt_generic_init($td, $key, $iv);
       /* Decrypt encrypted string */
       $decrypted = mdecrypt_generic($td, $encrypted);
       /* Terminate decryption handle and close module */
       mcrypt_generic_deinit($td);
       mcrypt_module_close($td);
       /* Show string */
       echo trim($decrypted) . "\n";
   ?>

   The first line in the example above will try to open the DES cipher
   from the default directory and the EBC mode from the directory
   /usr/lib/mcrypt-modes. The second example uses strings as name for the
   cipher and mode, this only works when the extension is linked against
   libmcrypt 2.4.x or 2.5.x.

   See also mcrypt_module_close(), mcrypt_generic(), mdecrypt_generic(),
   mcrypt_generic_init(), and mcrypt_generic_deinit().
   ______________________________________________________________________

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