string mcrypt_create_iv(int $size[, int $source = MCRYPT_DEV_URANDOM])
This function was DEPRECATED in PHP 7.1.0.
Alternatives to this function include:random_bytes()
Creates an initialization vector (IV) from a random source.
The IV is only meant to give an alternative seed to the encryption routines. This IV does not need to be secret at all, though it can be desirable. You even can send it along with your ciphertext without losing security.
Returns the initialization vector, or
FALSE on error.
- int $size: The size of the IV.
- int $source [ = MCRYPT_DEV_URANDOM]: The source of the IV. The source can be
MCRYPT_RAND(system random number generator),
MCRYPT_DEV_RANDOM(read data from /dev/random) and
MCRYPT_DEV_URANDOM(read data from /dev/urandom). Prior to 5.3.0,
MCRYPT_RANDwas the only one supported on Windows.
Note that the default value of this parameter was
MCRYPT_DEV_RANDOMprior to PHP 5.6.0.
Note: Note that
MCRYPT_DEV_RANDOMmay block until more entropy is available.
Example #1 mcrypt_create_iv() Example
$size = mcrypt_get_iv_size(MCRYPT_CAST_256, MCRYPT_MODE_CFB);
$iv = mcrypt_create_iv($size, MCRYPT_DEV_RANDOM);
- Note that MCRYPT_DEV_RANDOM may block until more entropy is available.
|5.3.0||It is no longer required to call srand() first. This is now done automatically.|