mcrypt_module_open This function opens the module of the algorithm and the mode to be used resourcemcrypt_module_open stringalgorithm stringalgorithm_directory stringmode stringmode_directory This function opens the module of the algorithm and the mode to be used. The name of the algorithm is specified in algorithm, eg "twofish" or is one of the MCRYPT_ciphername constants. The library is closed by calling mcrypt_module_close, but there is no need to call that function if mcrypt_generic_end is called. 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 directory are used that are compiled in into libmcrypt (usally /usr/local/lib/libmcrypt). ]]> The above example will try to open the DES cipher from the default directory and the EBC mode from the directory /usr/lib/mcrypt-modes.