mcrypt_module_is_block_algorithm_mode This function returns if the the specified module is a block algorithm or not boolmcrypt_module_is_block_algorithm_mode stringmode stringlib_dir This function returns &true; if the mode is for use with block algorithms, otherwise it returns &false;. (eg. &false; for stream, and &true; for cbc, cfb, ofb). The optional lib_dir parameter can contain the location where the mode module is on the system.