(PHP 8 >= 8.2.0)
openssl_cipher_key_length — Gets the cipher key length
cipher_algoThe cipher method, see openssl_get_cipher_methods() for a list of potential values.
Returns the cipher length on success, 或者在失败时返回 false.
Emits an E_WARNING level error when the cipher algorithm
is unknown.
示例 #1 openssl_cipher_key_length() example
<?php
$method = 'AES-128-CBC';
var_dump(openssl_cipher_key_length($method));
?>以上示例的输出类似于：
int(16)