The return value is a length in bytes. (Not bits, or anything else.)
(PHP 5 >= 5.3.3, PHP 7, PHP 8)
openssl_cipher_iv_length — Obtener la longitud del iv de cipher
Obtiene la longitud del vector de inicialización (iv) de cipher.
methodEl método de cipher, véase openssl_get_cipher_methods() para una lista de valores potenciales.
Devuelve la longitud de cipher en caso de éxito, o false en caso de error.
Emite un error de nivel E_WARNING cuando el algoritimo de cipher
es desconocido.
Ejemplo #1 Ejemplo de openssl_cipher_iv_length()
<?php
$método = 'AES-128-CBC';
$longitud_iv = openssl_cipher_iv_length($método);
echo $longitud_iv;
?>El resultado del ejemplo sería algo similar a:
16
<?php$ciphers = openssl_get_cipher_methods();//ECB mode should be avoided$ciphers = array_filter($ciphers, function ($n) { return stripos($n, "ecb") === FALSE;}); // At least as early as Aug 2016, Openssl declared the following weak: RC2, RC4, DES, 3DES, MD5 based$ciphers = array_filter($ciphers, function ($c) { return stripos($c, "des") === FALSE;});$ciphers = array_filter($ciphers, function ($c) { return stripos($c, "rc2") === FALSE;});$ciphers = array_filter($ciphers, function ($c) { return stripos($c, "rc4") === FALSE;});$ciphers = array_filter($ciphers, function ($c) { return stripos($c, "md5") === FALSE;});if (is_array($ciphers)) { foreach ($ciphers as $cipher) { echo $cipher.': '; echo openssl_cipher_iv_length($cipher); echo "<br>\n"; }}?>Will be...AES-xxx-xxx is 16BF-xxx is 8CAMELLIA-xxx is 16CAST5-xxx is 8IDEA-xxx is 8SEED-xxx is 16lower case:aes-xxx-xxx are mixed between 16 and 12.id-aes-xxx are mixed between 12 and 8.The values above are tested with PHP 5.5 - 5.6 on Windows. In PHP 7.x is different than this.