Subject: Re: bug#9036: [PATCH] gnutls: Add option to set minimum acceptable Diffie-Hellman key size

From: Lawrence Mitchell <[email-masked]>
Date: Thu, 10 Nov 2011 15:21:54 +0000

Lars Magne Ingebrigtsen wrote:
> Lawrence Mitchell <[email-masked]> writes:

>> The handshake returns GNUTLS_E_DH_PRIME_UNACCEPTABLE if the
>> number of server prime bits is too low.  I don't know how to
>> query the size of the server prime.  Maybe
>> gnutls_dh_get_prime_bits?  I'm wary to automatically adjust
>> downwards.

> I think adjusting it downwards automatically until you reach a
> (user-definable) absolute lower limit would be fine.  But I have no idea
> what an acceptable default lower limit would be, or what the impact on
> security this would have.

>> A better error message (pointing at the existance of
>> gnutls-min-prime-bits) in the case of this failure mode would
>> probably be good though.  I'll try and cook up a patch in the
>> next few days.

> Great!

So it turns out this wasn't a few days.

And I couldn't figure out a nice way to fix things up properly.
So no patch sorry :(.  However, I think the original bug can be
closed, because there is now an option to set the DH key size.

Lawrence
-- 
Lawrence Mitchell <[email-masked]>