mcrypt_enc_is_block_algorithm(3) php man page | unix.com

MCRYPT_ENC_IS_BLOCK_ALGORITHM(3)					 1					  MCRYPT_ENC_IS_BLOCK_ALGORITHM(3)

mcrypt_enc_is_block_algorithm - Checks whether the algorithm of the opened mode is a block algorithm

SYNOPSIS
       bool mcrypt_enc_is_block_algorithm (resource  $td)

DESCRIPTION
	Tells whether the algorithm of the opened mode is a block algorithm.

PARAMETERS
	      o $td
		- The encryption descriptor.

RETURN VALUES
	Returns TRUE if the algorithm is a block algorithm or FALSE if it is a stream one.

PHP Documentation Group 											  MCRYPT_ENC_IS_BLOCK_ALGORITHM(3)