mcrypt_get_cipher_name
mcrypt_get_key_size
Mcrypt Functions
PHP Manual

# mcrypt_get_iv_size

(PHP 4 >= 4.0.2, PHP 5)

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

### Descripción

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().

### Lista de parámetros

`cipher`

  One of the MCRYPT_ciphername constants of the name of the algorithm as string.

`mode`

  `mode` is one of the MCRYPT_MODE_modename constants or one of "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.

### Valores retornados

Returns the size of the Initialisation Vector (IV) in bytes. On error the function returns `FALSE`. If the IV is ignored in the specified cipher/mode combination zero is returned.

### Ejemplos

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";
?>`

### Ver también

- mcrypt_get_block_size() - Obtiene el tamaño de bloque del cifrado indicado
- mcrypt_enc_get_iv_size() - Returns the size of the IV of the opened algorithm
- mcrypt_create_iv() - Crea un vector de inicialización (IV) a partir de una fuente aleatoria

mcrypt_get_cipher_name
mcrypt_get_key_size
Mcrypt Functions
PHP Manual