(PHP 4 >= 4.0.2, PHP 5)
mcrypt_module_get_supported_key_sizes -- Returns an array with the supported keysizes of the opened algorithmReturns an array with the key sizes supported by the specified algorithm. If it returns an empty array then all key sizes between 1 and mcrypt_module_get_algo_key_size() are supported by the algorithm. The optional lib_dir parameter can contain the location where the mode module is on the system.
See also mcrypt_enc_get_supported_key_sizes() which is used on open encryption modules.