mcrypt_get_iv_size

(PHP 4 >= 4.0.2, PHP 5, PHP 7)

mcrypt_get_iv_sizeReturns the size of the IV belonging to a specific cipher/mode combination

Beschreibung

int mcrypt_get_iv_size ( string $cipher , string $mode )

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().

Parameter-Liste

cipher

Eine der Konstanten von MCRYPT_ciphername oder der Name eines Algorithmus als Zeichenkette.

mode

Eine der Konstanten von MCRYPT_MODE_modename oder eine der folgenden Zeichenketten: "ecb", "cbc", "cfb", "ofb", "nofb" oder "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.

R├╝ckgabewerte

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.

Beispiele

Beispiel #1 mcrypt_get_iv_size() Example

<?php
    
echo mcrypt_get_iv_size(MCRYPT_CAST_256MCRYPT_MODE_CFB) . "\n";

    echo 
mcrypt_get_iv_size('des''ecb') . "\n";
?>

Siehe auch

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User Contributed Notes 1 note

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Hernanibus
3 months 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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