mcrypt_get_iv_size
(PHP 4 >= 4.0.2, PHP 5)
mcrypt_get_iv_size — Returns the size of the IV belonging to a specific cipher/mode combination
Description
int mcrypt_get_iv_size
( string $cipher
, string $mode
)
cipher
is one of the MCRYPT_ciphername
constants of the name of the algorithm as string.
mode
is one of the MCRYPT_MODE_modename constants
or one of "ecb", "cbc", "cfb", "ofb", "nofb" or "stream". The IV is
ignored in ECB mode as this mode does not require it. You will need to
have the same IV (think: starting point) both at encryption and
decryption stages, otherwise your encryption will fail.
It is more useful to use the mcrypt_enc_get_iv_size()
function as this uses the resource returned by
mcrypt_module_open().