mcrypt_enc_is_block_mode(3) php man page | unix.com

MCRYPT_ENC_IS_BLOCK_MODE(3)						 1					       MCRYPT_ENC_IS_BLOCK_MODE(3)

mcrypt_enc_is_block_mode - Checks whether the opened mode outputs blocks

SYNOPSIS
       bool mcrypt_enc_is_block_mode (resource	$td)

DESCRIPTION
	Tells whether the opened mode outputs blocks (e.g.  TRUE for cbc and ecb, and FALSE for cfb and stream).

PARAMETERS
	      o $td
		- The encryption descriptor.

RETURN VALUES
	Returns TRUE if the mode outputs blocks of bytes, or FALSE if it outputs just bytes.

PHP Documentation Group 											       MCRYPT_ENC_IS_BLOCK_MODE(3)