(PHP 4 >= 4.0.2, PHP 5)
mcrypt_enc_get_supported_key_sizes — Returns an array with the supported keysizes of the opened algorithm
Gets the supported key sizes of the opened algorithm.
The encryption descriptor.
Returns an array with the key sizes supported by the algorithm specified by the encryption descriptor. If it returns an empty array then all key sizes between 1 and mcrypt_enc_get_key_size() are supported by the algorithm.
Example #1 mcrypt_enc_get_supported_key_sizes() example 以上例程会输出：
<?php
$td = mcrypt_module_open('rijndael-256', '', 'ecb', '');
var_dump(mcrypt_enc_get_supported_key_sizes($td));
?>
array(3) {
[0]=>
int(16)
[1]=>
int(24)
[2]=>
int(32)
}