mcrypt_enc_is_block_algorithm_mode Checks whether the encryption of the opened mode works on blocks &warn.deprecated.function-7-1-0; &reftitle.description; boolmcrypt_enc_is_block_algorithm_mode resourcetd Tells whether the algorithm of the opened mode works on blocks (e.g. &false; for stream, and &true; for cbc, cfb, ofb).. &reftitle.parameters; td The encryption descriptor. &reftitle.returnvalues; Returns &true; if the mode is for use with block algorithms, otherwise it returns &false;.