PHPerKaigi 2024

mcrypt_get_iv_size

(PHP 4 >= 4.0.2, PHP 5, PHP 7 < 7.2.0, PECL mcrypt >= 1.0.0)

mcrypt_get_iv_sizeReturns 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

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().

Parâmetros

cipher

Uma das constantes MCRYPT_nome_da_cifra ou o nome do algoritmo como string.

mode

Uma das constantes MCRYPT_MODE_nome_do_modo ou 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

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User Contributed Notes 1 note

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-5
Hernanibus
7 years ago
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
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