PHP 5.6.16 is available


(PHP 4 >= 4.0.2, PHP 5)

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


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().



MCRYPT_ciphername 상수 중 하나이거나, 알고리즘 이름 문자열.


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.


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.


Example #1 mcrypt_get_iv_size() Example

echo mcrypt_get_iv_size(MCRYPT_CAST_256MCRYPT_MODE_CFB) . "\n";

mcrypt_get_iv_size('des''ecb') . "\n";


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