openssl_cipher_iv_length

(PHP 5 >= 5.3.3, PHP 7, PHP 8)

openssl_cipher_iv_length — Gets the cipher iv length

function openssl_cipher_iv_length(string $cipher_algo): int|false

Gets the cipher initialization vector (iv) length.

cipher_algo: The cipher method, see openssl_get_cipher_methods() for a list of potential values.

Returns the cipher length on success, or false on failure.

Emits an E_WARNING level error when the cipher algorithm is unknown.

Example #1 openssl_cipher_iv_length() example

<?php
$method = 'AES-128-CBC';
$ivlen = openssl_cipher_iv_length($method);

echo $ivlen;
?>

The above example will output something similar to: