mcrypt_get_block_size Get the block size of the specified cipher intmcrypt_get_block_size intcipher intmcrypt_get_block_size stringcipher stringmodule The first prototype is when linked against libmcrypt 2.2.x, the second when linked against libmcrypt 2.4.x. mcrypt_get_block_size is used to get the size of a block of the specified cipher. mcrypt_get_block_size takes one or two arguments, the cipher and module, and returns the size in bytes. See also: mcrypt_get_key_size.