[PATCH] When generating the token, don't use a weak PRNG.

[Jouni Malinen]

On Wed, Jan 27, 2016 at 03:45:00PM +0000, Nick Lowe wrote:
> When generating the token, don't use a weak PRNG.

Why?

RFC 5931 has this to say about the token:

   The value of the anti-clogging token MUST be unpredictable and SHOULD
   NOT be from a source of random entropy.  The purpose of the anti-
   clogging token is to provide the server an assurance that the peer
   constructing the EAP-pwd-ID/Response is genuine and not part of a
   flooding attack.

Note especially that SHOULD NOT part..

> -    data->token = os_random();
> +    if (os_get_random((u8 *) &data->token, sizeof(data->token)) < 0) {

os_get_random() would seem to do exactly what that SHOULD NOT is
recommending against. Why would os_random() not be appropriate thing to
use here?
 
-- 
Jouni Malinen                                            PGP id EFC895FA