mcrypt_create_iv - Creates an initialization vector (IV) from a random source
Вернуться к: Mcrypt
mcrypt_create_iv
(PHP 4, PHP 5, PHP 7)
mcrypt_create_iv — Creates an initialization vector (IV) from a random source
Описание
$size
[, int $source = MCRYPT_DEV_URANDOM
] )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.
Список параметров
-
size -
The size of the IV.
-
source -
The source of the IV. The source can be
MCRYPT_RAND(system random number generator),MCRYPT_DEV_RANDOM(read data from /dev/random) andMCRYPT_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.Замечание: Note that
MCRYPT_DEV_RANDOMmay block until more entropy is available.
Возвращаемые значения
Returns the initialization vector, or FALSE on error.
Список изменений
| Версия | Описание |
|---|---|
| 5.6.0 |
MCRYPT_DEV_URANDOM is now the default value of
source.
|
| 5.3.0 |
MCRYPT_DEV_RANDOM and
MCRYPT_DEV_URANDOM became available on Windows
platforms.
|
| 5.3.0 | It is no longer required to call srand() first. This is now done automatically. |
Примеры
Пример #1 mcrypt_create_iv() Example
<?php
$size = mcrypt_get_iv_size(MCRYPT_CAST_256, MCRYPT_MODE_CFB);
$iv = mcrypt_create_iv($size, MCRYPT_DEV_RANDOM);
?>
Смотрите также
- » http://www.ciphersbyritter.com/GLOSSARY.HTM#IV
- » http://www.quadibloc.com/crypto/co0409.htm
- Chapter 9.3 of Applied Cryptography by Schneier (ISBN 0-471-11709-9)
- random_bytes() - Generates cryptographically secure pseudo-random bytes
Вернуться к: Mcrypt