mcrypt_get_iv_size
(PHP 4 >= 4.0.2, PHP 5, PHP 7 < 7.2.0, PECL mcrypt >= 1.0.0)
mcrypt_get_iv_size — Returns the size of the IV belonging to a specific cipher/mode combination
This function has been DEPRECATED as of PHP 7.1.0 and REMOVED as of PHP 7.2.0. Relying on this function is highly discouraged.
Description
mcrypt_get_iv_size ( string $cipher , string $mode ) : int
Gets the size of the IV belonging to a specific cipher/mode combination.
It is more useful to use the mcrypt_enc_get_iv_size() function as this uses the resource returned by mcrypt_module_open().
Parameters
-
cipher -
One of the
MCRYPT_ciphernameconstants, or the name of the algorithm as string. -
mode -
One of the
MCRYPT_MODE_modenameconstants, or one of the following strings: "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.
Return Values
Returns the size of the Initialization Vector (IV) in bytes. On error the function returns false. If the IV is ignored in the specified cipher/mode combination zero is returned.
Examples
Example #1 mcrypt_get_iv_size() Example
<?php
echo mcrypt_get_iv_size(MCRYPT_CAST_256, MCRYPT_MODE_CFB) . "\n";
echo mcrypt_get_iv_size('des', 'ecb') . "\n";
?> See Also
- mcrypt_get_block_size() - Gets the block size of the specified cipher
- mcrypt_enc_get_iv_size() - Returns the size of the IV of the opened algorithm
- mcrypt_create_iv() - Creates an initialization vector (IV) from a random source
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https://www.php.net/manual/en/function.mcrypt-get-iv-size.php