# mcrypt_module_open

(PHP 4 >= 4.0.2, PHP 5, PHP 7 < 7.2.0, PECL mcrypt >= 1.0.0)

mcrypt_module_open — Opens the module of the algorithm and the mode to be used

Warning

This function has been DEPRECATED as of PHP 7.1.0. Relying on this function is highly discouraged.

### Description

mcrypt_module_open ( string `$algorithm` , string `$algorithm_directory` , string `$mode` , string `$mode_directory` ) : resource

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().

### Parameters

`algorithm`

  One of the `MCRYPT_ciphername` constants, or the name of the algorithm as string.

`algorithm_directory`

  The `algorithm_directory` parameter is used to locate the encryption module. When you supply a directory name, it is used. When you set it to an empty string (""), the value set by the mcrypt.algorithms_dir php.ini directive is used. When it is not set, the default directory that is used is the one that was compiled into libmcrypt (usually /usr/local/lib/libmcrypt).

`mode`

  One of the `MCRYPT_MODE_modename` constants, or one of the following strings: "ecb", "cbc", "cfb", "ofb", "nofb" or "stream".

`mode_directory`

  The `mode_directory` parameter is used to locate the encryption module. When you supply a directory name, it is used. When you set it to an empty string (""), the value set by the mcrypt.modes_dir php.ini directive is used. When it is not set, the default directory that is used is the one that was compiled-in into libmcrypt (usually /usr/local/lib/libmcrypt).

### Return Values

Normally it returns an encryption descriptor, or `FALSE` on error.

### Examples

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 ECB 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.

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, use MCRYPT_RAND
* on Windows instead */
$iv = mcrypt_create_iv(mcrypt_enc_get_iv_size($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";
?>`

### See Also

- mcrypt_module_close() - Closes the mcrypt module
- mcrypt_generic() - This function encrypts data
- mdecrypt_generic() - Decrypts data
- mcrypt_generic_init() - This function initializes all buffers needed for encryption
- mcrypt_generic_deinit() - This function deinitializes an encryption module