The size of the initialization vector (iv) will be returned in bytes NOT bits, something to keep in mind specially if the iv is passed together appended or prepended with the encrypted data for decryption
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
Aviso
Esta função tornou-se DEFASADA a partir do PHP 7.1.0 e foi REMOVIDA a partir do PHP 7.2.0. O uso desta função é fortemente desencorajado.
Descrição
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().
Parâmetros
-
cipher -
Uma das constantes
MCRYPT_nome_da_cifraou o nome do algoritmo como string. -
mode -
Uma das constantes
MCRYPT_MODE_nome_do_modoou uma das seguintes strings: "ecb", "cbc", "cfb", "ofb", "nofb" ou "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.
Valor Retornado
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.
Exemplos
Exemplo #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";
?>Veja Também
- 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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User Contributed Notes 1 note
Hernanibus ¶
8 years ago
