mcrypt_module_get_algo_key_size

(PHP 4 >= 4.0.2, PHP 5, PHP 7)

mcrypt_module_get_algo_key_size — Returns the maximum supported keysize of the opened mode

int mcrypt_module_get_algo_key_size ( string $algorithm [, string $lib_dir ] )

Gets the maximum supported keysize of the opened mode.

algorithm: The algorithm name.
lib_dir: This optional parameter can contain the location where the mode module is on the system.

This function returns the maximum supported key size of the algorithm specified in bytes.