mcrypt_module_is_block_mode(3) php man page | unix.com

MCRYPT_MODULE_IS_BLOCK_MODE(3)						 1					    MCRYPT_MODULE_IS_BLOCK_MODE(3)

mcrypt_module_is_block_mode - Returns if the specified mode outputs blocks or not

SYNOPSIS
       bool mcrypt_module_is_block_mode (string  $mode, [string  $lib_dir])

DESCRIPTION
	This  function	returns TRUE if the mode outputs blocks of bytes or FALSE if it outputs just bytes. (e.g.  TRUE for cbc and ecb, and FALSE
       for cfb and stream).

PARAMETERS
	      o $mode
		-One of the MCRYPT_MODE_modename constants, or one of the following strings: "ecb", "cbc", "cfb", "ofb", "nofb" or "stream".

	      o $lib_dir
		- The optional $lib_dir parameter can contain the location where the algorithm module is on the system.

RETURN VALUES
	This function returns TRUE if the mode outputs blocks of bytes or FALSE if it outputs just bytes. (e.g.  TRUE for cbc and ecb,	and  FALSE
       for cfb and stream).

PHP Documentation Group 											    MCRYPT_MODULE_IS_BLOCK_MODE(3)