mcrypt_get_iv_size

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

mcrypt_get_iv_size — Returns the size of the IV belonging to a specific cipher/mode combination

설명

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().

인수

cipher

MCRYPT_ciphername 상수 중 하나이거나, 알고리즘 이름 문자열.

mode

MCRYPT_MODE_modename 상수 중 하나이거나, 다음 문자열 중 하나: "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.

반환값

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.

예제

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";
?>

참고

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

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Hernanibus ¶

8 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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